Organic-inorganic hybrid poly(methyl silsesquioxane) with a low curing temperature of 150 degrees C synthesized by a sol-gel method is employed as a gate dielectric for solution-based organic field-effect transistors. The device exhibits mobility enhancement, compared with those with SiO2 dielectrics, and hysteresis-free, highly stable operation, which is attributed to extremely low concentration of silanol groups of the poly(methyl silsesquioxane) dielectric.