It has been discovered that the incorporation of small amounts of hydrogen silsesquioxaneco-octadecyl silsesquioxane resin into hydrogen silsesquioxane films results in a significant modification of the thermally processed thin film properties compared to standard hydrogen silsesquioxane (HSQ) films derived from FOx ® solutions. These modifications included a doubling of the modulus and significant reduction in the remaining silyl hydride level. Key to the change in properties was an accelerated oxidation of the film during a one-minute hot plate bake step under a partial oxygen atmosphere. A systematic examination of a series of 5 to 30 weight percent resin additive formulations showed improved mechanical properties at lower additive levels but these were neutralized at higher levels by increasing levels of nanoporosity. It is hypothesized that the enhanced oxidation effect is the result of increased oxygen diffusivity into the film facilitated by the hydrocarbon component of the resin additive.