Hi Anja,

I remembered ammonia, in fact you can find confirmation here:

http://www.engineeringtoolbox.com/specific-heat-fluids-d_151.html

Best,

Nello

Cool, thank you very much for the quick answers!

On a mass basis hydrogen gas has more than three times the specific heat as water under normal laboratory conditions. Diatomic gases under ambient conditions generally have a molar specific heat of about 7cal/(mol K), and one mole of hydrogen has only 2g mass. Thus 3.5cal/(g K) for hydrogen versus 1cal/(g K) for water.

you can find the heat capacity is different for the different the substance