The influence of chemical quality on decomposition was studied under Mediterranean conditions using litter bag methodology. Litter of twenty-seven organic materials of different origins was enclosed in litterbags, buried, and periodically sampled during a 14-month period. The mass loss of each material was calculated, different empirical models of one and two pools were adjusted, and the respective constants were estimated. Linear regressions were established between the labile (ML) and recalcitrant (MR) mass loss pools and initial material characteristics to determine the best predictor of decomposition. ML and MR pools were related to the presence of soluble or recalcitrant compounds, with values varying between 66.7-685 and 316-934 g kg-1, respectively. Materials with higher soluble compounds, such as PMM or LL, showed significantly higher ML values than CSS or OWM materials, with higher MR values where recalcitrant fractions were predominant. Various quality parameters were correlated with mass loss with best predictability of ML and MR presented by labile indicators as TAPPI soluble elements that explained 79% and 77% of variation results, respectively. For structural parameters, the best result was presented by total condensed tannins followed by lignin content that explained between 40% and 51% variation of ML and MR. An Improved predictability was observed by integrating other labile indicators, liked water soluble C and N and the respective ratio, or recalcitrant total condensed tannins and holocellulose, in ML (r2adj=0.890***) and MR (r2adj=0.866***) pool estimation, respectively.