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Refrigerants & gases

Hydrogen · H2

Hydrogen (H2, CAS 1333-74-0) is an industrial and utility gas; this page gives its density, heat capacity and viscosity from 1 to 700 bar and -20 to 100 °C.

Values are computed from CoolProp==6.6.0 - reference Helmholtz equation of state for Hydrogen (single-phase density, isobaric heat capacity and dynamic viscosity) and tabulated over 1–700 bar (absolute) and -20–100 °C.

Also known as
H2, dihydrogen, normal hydrogen, GH2
CAS number
1333-74-0
Tabulated range
1–700 bar · -20–100 °C
Identity
Molar mass
2.016g/mol
Critical temperature
-240°C
Critical pressure
12.964bar
Normal boiling point
-252.78°C

NIST Chemistry WebBook, SRD 69 - Thermophysical Properties of Fluid Systems. NIST Chemistry WebBook, SRD 69, Thermophysical Properties of Fluid Systems, hydrogen (H2, CAS 1333-74-0): molar mass, critical point and normal boiling point. https://webbook.nist.gov/cgi/fluid.cgi?ID=C1333740&Action=Page

At 25 °C
reference snapshot
Density · 1 bar
0.0813kg/m³
Density · 700 bar
39.22kg/m³
Heat capacity · 1 bar
14306J/kg·K
Viscosity · 1 bar
8.900uPa.s
Compressibility · 700 bar
1.451Z
Explore

Read a value at any pressure and temperature

Set a pressure (bar absolute) and a temperature (°C) to interpolate between the tabulated grid points. The readout and chart never go outside the validated 1–700 bar and -20–100 °C range, and every number is interpolated from the committed table below — nothing is computed from an equation of state in your browser.

Interactive explorer

Values are interpolated between the tabulated grid points below — pressure (bar absolute) and temperature (°C) stay within the validated 1–700 bar and -20–100 °C range and are never extrapolated.

1 bar
25 °C
Density
0.0813 kg/m³
Specific volume
12.30 m³/kg
Compressibility Z
1.0003
Heat capacity
14306 J/kg·K
Viscosity
8.900 uPa.s
Density (kg/m³) vs pressure (bar) for H2 at 25 °C — Hydrogen.
Full tables

Every tabulated point

Rows are temperature (°C); columns are pressure (bar absolute). Read the cell at the intersection. Density is the single-phase fluid density at that state.

Density — kg/m³
°C \ bar125102050100200350500700
-200.09570.19130.47740.95171.89124.63768.978016.8126.7434.9343.90
00.08870.17730.44240.88221.75354.30358.344515.6925.0932.9741.69
150.08410.16810.41950.83641.66284.08337.926514.9423.9931.6440.17
250.08130.16240.40540.80841.60753.94887.670914.4823.3230.8139.22
500.07500.14990.37410.74611.48403.64897.100113.4521.7828.9337.04
750.06960.13910.34730.69271.37823.39176.609812.5620.4427.2735.10
1000.06490.12980.32410.64651.28653.16876.183811.7919.2625.7933.35
Isobaric heat capacity — J/kg·K
°C \ bar125102050100200350500700
-201407614080140921411214151142601441514636148281492714988
01419814201142111422814261143531448514680148551495315020
151426814271142801429514324144061452414701148651496115030
251430614309143171433114358144341454514711148681496115032
501438014382143891440014423144861457914723148631495115021
751442814430144361444514464145181459714722148471492814996
1001445914460144651447314489145351460314712148241489914964
Dynamic viscosity — uPa.s
°C \ bar125102050100200350500700
-207.9477.9487.9517.9567.9688.0148.1218.4249.0159.68310.617
08.3778.3788.3808.3848.3948.4328.5248.7909.3189.92810.793
158.6938.6938.6958.6998.7078.7418.8239.0659.55310.12510.944
258.9008.9018.9038.9068.9138.9459.0219.2489.71310.26011.052
509.4109.4119.4129.4149.4209.4469.5109.70610.11810.61411.342
759.9089.9099.9099.9119.9169.9369.99110.16210.52910.98111.655
10010.39610.39610.39710.39810.40110.41810.46410.61410.94511.35811.986
Typical values

Hydrogen density at pressure (25 °C)

At 100 bar and 25 °C, hydrogen density is about 7.7 kg/m³. At 200 bar and 25 °C, hydrogen density is about 14.5 kg/m³. At 350 bar and 25 °C, hydrogen density is about 23.3 kg/m³. At 500 bar and 25 °C, hydrogen density is about 30.8 kg/m³. At 700 bar and 25 °C, hydrogen density is about 39.2 kg/m³.

Sources

Where the numbers come from

Every value on this page is computed by a deterministic equation of state — none is entered by hand. The generating method and the references it is checked against:

  • ▸NIST Chemistry WebBook, SRD 69 - Thermophysical Properties of Fluid Systems (REFPROP-derived isothermal tables), hydrogen (CAS 1333-74-0)
  • ▸CoolProp 6.6.0 - reference Helmholtz equation of state for Hydrogen (Leachman, Jacobsen, Penoncello & Lemmon, 2009); dynamic viscosity from the Muzny, Huber & Kazakov, 2013 model

Model: CoolProp==6.6.0 - reference Helmholtz equation of state for Hydrogen (single-phase density, isobaric heat capacity and dynamic viscosity) · Generated 2026-06-07

The committed data file for this page is published as JSON on GitHub under CC BY 4.0.

Validation

Checked against cited values

The equation of state is cross-checked against independently cited NIST WebBook reference points — a near-ambient and a compressed density, plus the heat-capacity and viscosity columns. The page is published only because every check passes.

Property / pointDensity · 1 bar · 25 °C
Cited reference value0.0813 kg/m3
Model computed0.0813 kg/m3
Error vs reference0% (tolerance 1%)

NIST Chemistry WebBook, SRD 69 - Thermophysical Properties of Fluid Systems. NIST Chemistry WebBook, SRD 69, Thermophysical Properties of Fluid Systems, hydrogen (H2, CAS 1333-74-0), isothermal table at 298.15 K: density at 1 bar = 0.081272 kg/m3. https://webbook.nist.gov/cgi/fluid.cgi?ID=C1333740&Action=Page

Property / pointDensity · 700 bar · 25 °C
Cited reference value39.223 kg/m3
Model computed39.2233 kg/m3
Error vs reference0.001% (tolerance 1%)

NIST Chemistry WebBook, SRD 69 - Thermophysical Properties of Fluid Systems. NIST Chemistry WebBook, SRD 69, Thermophysical Properties of Fluid Systems, hydrogen (H2, CAS 1333-74-0), isothermal table at 298.15 K: density at 700 bar = 39.223 kg/m3. https://webbook.nist.gov/cgi/fluid.cgi?ID=C1333740&Action=Page

Property / pointIsobaric heat capacity · 1 bar · 25 °C
Cited reference value14306 J/kg.K
Model computed14306.3 J/kg.K
Error vs reference0.002% (tolerance 2%)

NIST Chemistry WebBook, SRD 69 - Thermophysical Properties of Fluid Systems. NIST Chemistry WebBook, SRD 69, Thermophysical Properties of Fluid Systems, hydrogen (H2, CAS 1333-74-0), isothermal table at 298.15 K: isobaric heat capacity Cp at 1 bar = 14306 J/kg.K. https://webbook.nist.gov/cgi/fluid.cgi?ID=C1333740&Action=Page

Property / pointDynamic viscosity · 1 bar · 25 °C
Cited reference value8.9 uPa.s
Model computed8.9 uPa.s
Error vs reference0% (tolerance 2%)

NIST Chemistry WebBook, SRD 69 - Thermophysical Properties of Fluid Systems. NIST Chemistry WebBook, SRD 69, Thermophysical Properties of Fluid Systems, hydrogen (H2, CAS 1333-74-0), isothermal table at 298.15 K: dynamic viscosity at 1 bar = 8.9003 uPa.s. https://webbook.nist.gov/cgi/fluid.cgi?ID=C1333740&Action=Page

Limitations

Before you use these numbers

  • ▸CoolProp reference Helmholtz equation of state (Leachman, Jacobsen, Penoncello & Lemmon, 2009) for hydrogen; dynamic viscosity from the Muzny, Huber & Kazakov, 2013 model. Single-phase density, isobaric heat capacity and dynamic viscosity, tabulated on a 1-700 bar (absolute) by -20 to 100 degC grid; two-phase, saturation and liquid states are out of scope for this page. The correlation is not extrapolated beyond the tabulated range. Values are for preliminary design; verify against vendor or reference data for critical service.
  • ▸Every tabulated state is single-phase. A grid cell is left blank only where the state at that pressure and temperature would be two-phase or liquid - at or above the saturation pressure at that temperature - and the explorer will not interpolate across such a cell. Because the critical temperature of hydrogen is -240.0 degC, below the -20 degC floor of this grid, every (pressure, temperature) point tabulated here is a supercritical single-phase fluid, so no cell is blank.
  • ▸Values are tabulated only inside the 1–700 bar and -20–100 °C ranges shown; the equation of state is not extrapolated beyond them here.
  • ▸Use for preliminary design; verify for critical service.
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