A kind of nonfunctional oligomeric silsesquioxane (SSQ), methyl silsesquioxane (Me-SSQ), was used to modify cyanate ester (CE) resin in this article. First, Me-SSQ was synthesized by the hydrolysis and condensation of methyltriethoxysilane. Then, a series of Me-SSQ/CE hybrids containing 0, 1, 5, 10, and 20 wt % of Me-SSQ were prepared. The effect of Me-SSQ content on the reactivity, mechanical, dielectric, thermal, and hot/wet properties of materials was investigated. Fourier transform infrared spectroscopy was used to study the reactivity of hybrid CE resin systems, indicating that the addition of Me-SSQ does not show significant effect on the conversion of CE. Mechanical and dielectric properties of the Me-SSQ/CE hybrid materials were also studied. Impact strength of the Me-SSQ/CE hybrids reaches its maximum value when Me-SSQ content is 5 wt %. However, the flexural strength reaches the maximum value when Me-SSQ content is 1 wt %. The Me-SSQ/CE hybrid containing 20 wt % of Me-SSQ shows a dielectric constant of 2.78, that is, much lower than the pure CE resin. At the same time, the dielectric loss of the Me-SSQ/CE hybrids was slightly increased (tan delta < 0.006). Therefore, Me-SSQ/CE hybrid is a promising candidate for high-performance printed circuit board matrix materials. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 121: 1004-1012, 2011