Open system non-isothermal (programmed) pyrolysis was used to analyse the pyrolytic release of molecular nitrogen (N-2) and methane (CH4) from sedimentary rocks of different geological age, facies and depositional environments. Pyrogram patterns were compared and classified according to the specific release intensities (peaks) of the two gases as a function of temperature. Selected model substances, such as humic acid and tobelite (ammonium muscovite) were pyrolysed for reference purposes to assess the relative contributions of organic and inorganic species to the pyrolytic liberation of N-2. The peak patterns of the N-2 pyrograms were tentatively attributed to different inorganic or organic precursor components. They could be classified into five groups reflecting the different thermal stabilities of inorganic and organic nitrogen-containing components. The influence of maturity, sulphur content and depositional environment was investigated by systematic comparison of the N-2 and CH4 pyrograms. Methane pyrograms provided information on the relative content, composition and maturity of the organic matter of the sedimentary rocks. For a sample sequence from a stratigraphic Carboniferous shale unit the pyrolytic N-2 and CH4 generation patterns were recorded over an extended depth interval (791-1750 m) to monitor thermal maturity trends and facies variations and to study their impact on nitrogen geochemistry. (C) 2011 Elsevier B.V. All rights reserved.