This work reports the synthesis and characterization of diamantane-based polyimides obtained from 4,9-bis[4(3,4-dicarboxyphenoxy)phenyl]diamantane dianhydride and various aromatic diamines. Interestingly, the diamantane-based polyimides were very stable to hydrolysis. This novel polyimide exhibits a low dielectric constant (2.65-2.77), low moisture absorption (<0.67%), good solubility, high T, and unusually high thermal stability. Dynamic mechanical analysis (DMA) reveals that the diamantane-based polyimides have high T-g ranging from 281 to 379 degrees C. The high-temperature beta(1) subglass transition around 285 degrees C was observed in polyimide 6a derived from 2,2'-bis(trifluoromethyl)benzidine. This class of novel diamantane-based polyimide is very promising for electronic applications, because of its good mechanical properties, good thermal stability, low dielectric constant, excellent hydrolytic resistance, and low moisture absorption. (C) 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1673-1684, 2009