The effect of various functionality (di-, tetra-, pentafunctionality) on mechanical, thermal and moisture absorption properties of naphthalene containing epoxy resins cured with diaminodiphenylmethane (DDS) is investigated. It was found that the glass transition temperature, retention of elastic modulus, thermal stability and moisture absorption increased as the epoxy functionality increased, however, an inverse effect on thermal expansion was observed.In order to toughen the naphthalene containing epoxy network, the epoxy resin was partially vinylized with 2-allylphenol, followed by hydrosilation using hydride terminated siloxane oligomer. SEM photographs of the modified epoxy networks exhibited a phase separation and the introduction of siloxane into the epoxy backbone has effectively reduced internal stress of the cured products.