A study aimed to monitor the composting process and to evaluate the effectiveness of indicators able to define the stability of a compost obtained by mixing municipal solid waste (MSW) and vegetal waste, was conducted. For this reason, composting process lasting 3 months, was monitored by chemical and thermal analysis. Total organic carbon (TOC), total extractable carbon (TEC) and humic and fulvic acid carbon (HA and FA. respectively) were determined after extraction, fractionation and analysis of organic matter from samples collected during the composting process. Differential scanning calorimetry (DSC), thermogravimetry (TG) and the first derivative of the TG (DTG) were simultaneously performed in oxidizing conditions on grounded compost samples and HA extracted. Thermoanalitical data resulted to be useful in integrating quantitative information coming from chemical analysis of humified fraction of compost organic matter. Particularly DSC curves allowed to distinguish between well and poor stabilized organic matter, and information deriving from weight losses, registered by the TG and DTG curves, enable to individuate the evolution state of the organic matter and therefore its stability. (C) 2003 Elsevier B.V. All rights reserved.