The modified nylon 6/polypyrrole composite films were Prepared by exposing modified nylon 6matrix films containing cupric chloride to pyrrole vapor under various experimental conditions. The electrical conductivity and stability on ambient air exposure. thermal and mechanical properites of composite films were investigated. The results showed that the conductivity increased from 10% to 10-3 S/cm on exposing the matrix film containing 10 wt% cupric chloride to pyrrole vapor for 30 min at $25^{circ}C$. The saturation conductivity increased up to 102 S/cm when the same sample film was exposed to pyrrole vapor for 1 hr at $0^{circ}C$. The conductivity increase of composite aims prepared at low temperature was related to its morphology. The stability of conductivity was excellent: the conductivity has decreased within one order of magnitude on exposure to ambient air for 30 days. The thermal weight loss and the breaking strength loss of composite film were higher compared to the matrix films. especially when the composite film was prepared with the matrix film containing larger content of cupric chloride.