After polyglycerol polyglycidyl ether (PGPE) and glycerol polyglycidyl ether (GPE) were mixed with tannic acid (TA) in ethanol and without solvent at epoxy/hydroxyl ratio 1/1, the obtained GPE-TA and PGPE-TA solutions were mixed with wood flour (WF), prepolymerized at 50 degrees C, and subsequently compressed at 160 degrees C for 3 h to give GPE-TA/WF and PGPE-TA/WF biocomposites with WF content 50-70 wt %, respectively. The storage moduli of the biocomposites in the rubbery state at more than 80 degrees C were much higher than that of the control cured resins. The PGPE-TA/WF composites had higher tensile modulus and rather lower tensile strength than PGPE-TA. On the other hand, both the tensile modulus and strength of GPE-TA/WF were much higher than those of GPE-TA (2.4 GPa and 37 MPa). Those values of GPE-TA/WF increased with WF content, became maximal values (5.1 GPa and 51 MPa) at WF content 60 wt %, and were lowered at 70 wt %. FE-SEM analysis of the fractured surface of the biocomposites revealed that WF is tightly incorporated into the crosslinked epoxy resins. As a result of optimization of the epoxy/hydroxyl molar ratio for GPE-TA/WF composite with WF content 60 wt %, the composite prepared at the ratio of 1.0/0.8 showed the highest tensile modulus and strength. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 118: 2998-3004, 2010