In this study an attempt was made to obtain lower density of ethylene-vinyl acetate copolymer (EVA)/ethylene-1-butene copolymer (EtBC) foams without sacrificing mechanical properties. For this purpose EVA/EtBC/clay nanocomposite foams were prepared. To investigate the effect of compatibilizer and silane coupling agent on the physical properties of the EVA/EtBC/clay foams, maleic anhydride-grafted EtBC (EtBC-g-MAH) and the most commonly used silane coupling agent in rubbers, bis(3-triethoxysilylpropyl) tetrasulfide (Si-69) were used in the preparation of EVA/EtBC/clay nanocomposite foams. The formation of EVA/EtBC/clay nanocomposite foams was supported by X-ray diffraction results. And, using a compatibilzer and silane coupling agent, lower density of EVA/EtBC/clay nanocomposite foams were obtained without sacrificing mechanical properties except compression set. (c) 2006 Wiley Periodicals, Inc.