This work has been mainly focused on the development and optimization of the processing methodology to produce epoxy modified phenolic foams. This study analyzes the relation between the composition and the structure as well as the mechanical and flammability performance of epoxy-phenolic (E-P)-based foams. Phenolic foams modified with different types and compositions of epoxy resin were successfully synthesized and characterized, showing uniform pore structure. Two epoxy resins were used for this approach. One is regular diglycidyl ether of bisphenol A (Epon 826) type and the other is a brominated bisphenol A (DER 542), which has halogen groups in the structure to improve the flammability properties of the resulting foams. Cone calorimeter (ASTM E 1354) was used to measure the heat release rate, the time to ignition, and other flammability properties of the E-P foams with different types of epoxy resins, under well-controlled combustion conditions. The mechanical performance of the system was studied and compared with competing foams, such us phenolic, epoxy, and polyurethanes, in aspects of compression, friability, and shear performances. Compared with conventional phenolic foams, E-P foams exhibit significant improvement in mechanical performance, lower friability and similar resistance to flame. These results demonstrate the potential of the E-P foam as a flame resistant and high performance core material for sandwich structure. (c) 2007 Wiley Periodicals, Inc.