Com. polyamide 6 and a halloysite nanotubes-reinforced polyamide 6-matrix composite were studied for crystn. behaviour by differential scanning calorimetty to det. Avrami exponent, the kinetic crystn. rate const., the peak temp, and the half-time of crystn. at 250 degrees C and varying cooling rates (5-30 K/min). The halloysite nanotubes were active substrates for the heterogeneous nucleation but the crystn. rate was reduced.