Parthenium hysterophorus and Eichhornia crassipes are two uncontrolled weeds with high concentration of N, P, K, Zn and Fe that makes them suitable for composting. Three types of compost viz. Parthenium and Eichhornia each alone as well as combined were prepared. Biochemical and enzymatic analysis of the compost in addition to seed germination was performed. Phenols, organic carbon, C/N and C/P ratios were found to decrease significantly while N, P, K, polyphenol oxidase increased significantly in combined compost. Furthermore, seed germination test of Vigna radiata and Triticum seeds, revealed a significant increase in root, shoot length and germination index in 60 days old combined compost. It can be concluded that combined composting of Parthenium with Eichhornia not only reduces the allelopathic effect but also increases its nutrient quality and thus could be promising for organic farming and bioremediation. (C) 2012 Elsevier Ltd. All rights reserved.