The objective of this study was to evaluate the influence of substrate concentration and moisture content on the specific methanogenic activity (SMA) of a fresh dry mesophilic digestate from a municipal solid waste digester plant. For this purpose, SMA tests were performed under mesophilic conditions into glass bottles of 500 mL volume used as batch reactors, during a period of 20-25 days. Propionate was used as substrate at concentrations ranging from 1 to 10 gCOD/kg. Four moisture contents were studied: 65%, 75%, 80% and 82%. Experimental results showed that propionate concentration and moisture content strongly influenced the SMA. The highest SMA was observed at a substrate concentration of 10 gCOD/kg (11.3 mgCOD gVS(-1) d(-1) for the second dose of propionate) and at a moisture content of 82% (7.8 mgCOD gVS(-1) d(-1) for the second dose of propionate, at a concentration of 5 gCOD/kg). SMA was found to decrease linearly when decreasing the moisture content. (C) 2010 Elsevier Ltd. All rights reserved.