Abstract : CCP RF discharges are well known to be sources of dusty plasmas. These plasmas are used to simulate the formation of organic solid particles in planetary atmospheres, as Titan with an N2-CH4 mixture. As a first step for understanding these plasmas, we study here the formation of molecules, radicals and positive ions in an N2-H2 CCP RF plasma mixture. Radicals and positive ions are measured by in situ mass spectrometry. Neutrals are accumulated in a cold trap downstream the plasma. These molecules are measured, after warming the trap by mass spectrometry and IR absorption spectroscopy. When mass spectrometry gives relative values of species abundances, IR absorption gives absolute values of the most abundant molecules. A focus is done on NH3, this molecule being produced as well in the discharge as by catalytic effect on the metallic wall of the discharge.