In the study, polycyanurate (PCN)/epoxy resin (ER) blends are prepared to enhance the physical properties of cyanate ester resins. The effects of curing schedule and blend composition on their thermal, mechanical, and dielectrical properties of cured PCN/epoxy blend films are examined. FTIR analysis of the cured blend films exhibits the expected cyanurate and oxazolidinone peaks in all blend compositions except the film thermally treated for 1 h in the presence of 1% phenol. TGA results show that the thermal stability decreases with epoxy content in the blend film. From SEM analyses, it is observed that all films have very dense, smooth, and bubble free surface without phase separation. For the pure PCN, the dielectric constants are found to be 3.54-5.91 in the range of 10(-1)-10(7) Hz between 20 degrees C and 200 degrees C. PCN/epoxy blends up to 50% epoxy resin show a good stability of dielectric constant in this frequency band for 200 degrees C, which is close to the dielectric constant of the homopolymerized PCN. Beyond this percentage of epoxy resin, dielectric constants of PCN/epoxy blends greatly increase at low-frequency region (0.1-10(3) Hz) due to the interfacial polarization governed by Maxwell-Wagner-Sillars effect. POLYM. ENG. SCI., 58:820-829, 2018. (c) 2017 Society of Plastics Engineers