This work reports, for the first time, on the effect of carbon nanotubes (CNT) on the kinetics of the activated polymerization of lactams. Differential scanning calorimetry (DSC) was chosen to study the kinetics of the activated anionic polymerization of e-caprolactam in the presence of multiwalled carbon nanotubes (MWCNT). A statistical test was carried out to confirm the validity of the experimental approach. The presence of the MWCNT slowed down the polymerization rate. This inhibiting effect depended not only on the MWCNT content but also on its state of dispersion in the polymerizing system. An autocatalytic model coupled with an evolutionary algorithm showed that the MWCNT content had an effect on the autocatalysis while its state of dispersion had an effect on the apparent polymerization kinetic constant. POLYm. ENG. SCI., 50:2287-2297,2010. (C) 2010 Society of Plastics Engineers