The present paper compares Rock-Eval pyrolysis (RE), liquid chromatography (L.C), and gas chromatography-mass spectrometry (GC-MS) data from a geochemical study of Jebel Chaker organic-rich facies, in central-northern Tunisia, in order to obtain independent parameters on organic matter source, composition, and thermal maturity. This study shows a clear evidence of planktonic organic matter as indicated by the hydrogen index, n-alkanes distribution, predominance of saturated, and the high concentration of cholestane. The thermal maturity of Ypresian organic matter was estimated by T-max abundance of hetero (N.S.O) compounds, and sterane geochemical parameters such as C-29 alpha alpha 20S/(20S+20R) and C-29 beta beta (beta beta+alpha alpha) maturity ratios..., to be of low thermal maturity (end of diagenesis-beginning of catagenesis). These data reveal a close concordance between RE, L.C., and GUMS data, and show that these methods remain valuable and practical for geochemical characterization of sedimentary organic matter. (c) 2007 Elsevier B.V. All rights reserved.