The influence of self-immobilization of enriched acidogenic mixed consortia on fermentative hydrogen (H(2)) production was studied on different supporting materials [SBA-15 (mesoporous) and activated carbon (granular; GAC and powder; PAC)] using chemical wastewater as substrate. Batch fermentation experiments were performed with same substrate at different organic loading rates (OLRs) under acidophilic microenvironment (pH 5.5) and room temperature (28 +/- 2 degrees C). Experimental data evidenced the effectiveness of attached growth on both the H(2) yields and substrate degradation efficiency, particularly at higher loading rates. Among the three materials evaluated, immobilization on SBA-15 material showed comparatively effective performance in enhancing both H(2) yield and substrate degradation. Suspended growth (SG-control) culture showed inhibition in terms of both H(2) production and substrate degradation especially at applied higher loading rates. Immobilization on SBA-15 resulted in nine times higher H(2) production (7.29 mol/kg COD(R)-day at OLR of 0.83 kg COD/m(3)-day) than the lowest yield observed (suspended growth at OLR of 2.55 kg COD/m(3)-day). Maximum substrate degradation rate (SDR) of 0.96 kg COD/m(3)-day (OLR 2.55 kg COD/m(3)-day) was also observed with SBA-15 immobilization, which is 1.62 times higher than the lowest substrate degradation observed with SG-control experiments with the same OLR. Attached growth on GAC and PAC also showed remarkable improvement in the process performance at higher OLRs compared to SG-control. (C) 2008 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.