The reaction of 2,5-dimethylpiperazine with a double molar amount of maleic anhydride afforded a new unsaturated dicarboxylic acid that was characterized by IR and 1H-NMR spectroscopy. It was condensed with various aromatic diamines by the phosphorylation method to yield polyamides bearing olefinic bonds. They were readily soluble in polar aprotic solvents and certain acids. The DTA traces of polyamides showed exotherms above 250°C attributable to their cross-linking through the olefinic bonds and a partial thermal degradation. Evidence for the cross-linking of polyamides attained during their heat-curing was obtained from the IR spectra of the uncured and cured samples. Thermal stabilities of cured (at 300°C for 15 h) polyamides were evaluated by TGA and isothermal gravimetric analysis. They were stable up to 321–336°C in N2 or air and afforded an anserobic char yield of 61–71% at 800°C. © 1993 John Wiley & Sons, Inc.