A novel and facile method for the synthesis of high molecular weight polyimides by low temperature solution polycondensation has been developed. This activated polycondensation method is based on the use in situ of both chloro(trimethyl)silane (CTMS) and a base such as pyridine (Py) as polycondensation promoters. The polymers here described have been prepared by direct polycondensation of 4,4'-(hexafluoroisopropylidene)-diphthalic anhydride with a series of aromatic diamines of different reactivity, to demonstrate the feasibility of this synthetic method in polycondensation reactions. The effect in polyimidation reactions of the individual or combined use of CTMS and Py has been studied. The coupled use of CTMS and Py afforded polyimides having inherent viscosities up to 1.05 dLg(-1). Moreover, the formation of poly(amic acid silyl ester) took place in a shorter time than the classical reactions of dianhydrides and aromatic diamines. A quantum modeling study (DFT and semiempirical) has shown the influence of silylation on the reactivity of diamines. Also, it has permitted to study the pathways of the reaction, showing the necessity of a base to ensure that the formation of polyamic acid takes place.