Tools

Basic Hydrogen Properties Chart

Download the information in Excel format: Hydrogen Properties

Properties

Values

Units

Autoignition temperatureThe autoignition temperature depends on hydrogen concentration (minimum at stoichiometric combustion conditions), pressure, and even the surface characteristics of the vessel. See NFPA 2: Hydrogen Technologies Code 2016 Edition Annex D.

500

°C

932

°F

Boiling point (1 atm)NIST Chemistry WebBook

-252.9

°C

-423.2

°F

Density (NTP)NTP (normal temperature and pressure) = 20°C (68°F) and 1 atm. NIST Chemistry WebBook

0.08375

kg/m³

0.005229

lb/ft³

Diffusion coefficient in air (NTP)NTP (normal temperature and pressure) = 20°C (68°F) and 1 atm. National Aeronautical and Space Administration, Safety Standard for Hydrogen and Hydrogen Systems (NSS 1740.16), 1997

0.610

cm²/s

6.57 E-4

ft²/s

Enthalpy (NTP)NTP (normal temperature and pressure) = 20°C (68°F) and 1 atm. NIST Chemistry WebBook

3858.1

kJ/kg

1659.8

Btu/lb

EntropyNTP (normal temperature and pressure) = 20°C (68°F) and 1 atm. NIST Chemistry WebBook

53.14

J/g-K

12.70

Btu/lb-°R

Flame temperature in airNational Aeronautical and Space Administration, Safety Standard for Hydrogen and Hydrogen Systems (NSS 1740.16), 1997

2045

°C

3713

°F

Flammable range in airNTP (normal temperature and pressure) = 20°C (68°F) and 1 atm. National Aeronautical and Space Administration, Safety Standard for Hydrogen and Hydrogen Systems (NSS 1740.16), 1997

4.0 - 75.0

vol%

Ignition energy in airHydrogen Fuel Cell Engines and Related Technologies. Module 1: Hydrogen Properties. U.S. DOE. 2001

2.0 E-5

J

1.9 E-8

Btu

Internal Energy (NTP)NTP (normal temperature and pressure) = 20°C (68°F) and 1 atm. Reference state: Internal Energy U=0 at 273.16 K for saturated liquid; Entropy S=0 at 273.16 K for saturated liquid. NIST Chemistry WebBook

2648.3

kJ/kg

1139.3

Btu/lb

Molecular weightNIST Chemistry WebBook

2.02

Specific gravity (air = 1) (NTP)NTP (normal temperature and pressure) = 20°C (68°F) and 1 atm. Hydrogen Fuel Cell Engines and Related Technologies. Module 1: Hydrogen Properties. U.S. DOE. 2001

0.0696

Specific volume (NTP)NTP (normal temperature and pressure) = 20°C (68°F) and 1 atm. NIST Chemistry WebBook

11.94

m³/kg

191.26

ft³/lb

Specific heat at constant pressure, Cp (NTP)NTP (normal temperature and pressure) = 20°C (68°F) and 1 atm. NIST Chemistry WebBook

14.29

J/g-K

3.415

Btu/lb-°R

Specific heat at constant volume, Cv (NTP)NTP (normal temperature and pressure) = 20°C (68°F) and 1 atm. NIST Chemistry WebBook

10.16

J/g-K

2.428

Btu/lb-°R

Thermal conductivity (NTP)NTP (normal temperature and pressure) = 20°C (68°F) and 1 atm. NIST Chemistry WebBook

0.1825

W/m-K

0.1054

Btu/ft-h-°R

Viscosity (NTP)NTP (normal temperature and pressure) = 20°C (68°F) and 1 atm. NIST Chemistry WebBook

8.813 E-5

g/cm-sec

5.922 E-6

lb/ft-sec

Hydrogen Conversion Calculator

You may use this calculator to do simple conversions between four popular phase points of hydrogen

  • Liquid at boiling point (-252.87°C at 1 atm).
  • Gas at Normal Temperature and Pressure (NTP = 20°C at 1 atm).
  • Gas at standard conditions (15.6°C at 1 atm).
  • Gas at standard conditions (0°C at 1 atm).