Metathesis polymerization of N-phenyl-exo-norbornene dicarboximide and ortho/meta/para methyl substituted phenyl nadimides was carried out using WCl6/tetramethyltin. Structural characterization was done by FTIR, H-1- and C-13-NMR. A mixture of cis and trans double bond structures were introduced in the backbone during polymerization. The cis content was higher (52 to 65%). In the DSC scan of poly(N-o-tolyl nadimide), two exotherms were observed at 240 and 270 degrees C while in other samples only one exothermic transition was observed above 240 degrees C. These exotherms disappeared in the second heating cycle. The T-g of the polymers, as determined in the second heating cycle, was highest in poly(N-o-tolyl nadimide) and lowest in poly(N-m-tolyl nadimide). The polymers were stable up to 443 +/- 3 degrees C and decomposed above this temperature in a single step.