A microsphere templating process was recently developed for fabrication of open-cell porous elastomer. The material contained a unique cocontinuous structure having micropores interconnected by microchannels. In this work, a follow-up study was conducted to investigate the mechanical behavior of such porous materials. Polysiloxane was chosen as a model material. The deformation characteristics and mechanical properties of the porous elastomer under tension and compression were then studied. For both tensile and compressive tests, the mechanical properties measured were found to largely deviate from those calculated by the additive rule assuming affine deformation. This nonaffine mechanics was further verified by microscopic observations. Cyclic loading and unloading tests were also performed to study the hysteresis of the material. In comparison with the solid elastomer, the hysteresis of the porous elastomer was considerably higher and more sensitive to the strain rate. An attempt was further made to fit the stress-strain curve using existing hyperelastic models, and the results showed that the Arruda-Boyce model, in general, fit both the solid and porous polysiloxane very well. (C) 2013 Society of Plastics Engineers