AbstractSemirigid IPN foams were prepared by simultaneous polymerization (SIN technique) of urethane‐isocyanurate and epoxy resin systems. Significantly higher compressive strength was obtained with the IPN foams as compared to the corresponding urethane‐isocyanurate foams. Due to the relatively low functionality of the foam components, and hence, resulting low crosslink density of the IPN foams, the oxygen indices and the friability were relatively low but increased with increasing isocyanate index and epoxy content. Although these studies were preliminary in nature, this type of IPN foams could find applications in sound and noise attenuation as well as for energy absorption such as shock and vibration damping.