To use compost appropriately in agriculture it is extremely important to estimate the stabilization level of the organic matter. In this work, two different piles of compost were studied by means of (i) humification parameters (degree of humification-DH, humification rate-HR, humification index-HI) prior to and after enzymatic hydrolysis of the extracted organic carbon, (ii) water-soluble organic carbon (WSOC) and (iii) water-soluble nitrogen. A significant relationship between composting time, WSOC and humification parameters after enzymatic hydrolysis (DHenz; HRenz; HIenz) was found. (C) 2003 Elsevier Ltd. All rights reserved.