The influence of sample thickness on the fracture behaviour of an aliphatic polyketone and a blend of this polymer and 10 wt% core-shell rubber was studied. The sample thickness was varied from 0.1 to 8 mm. The skin morphology was studied by SEM. The fracture behaviour was studied on single edge notch specimen at a high strain rate (30 s(-1)) in the temperature range of -40 to 120 degrees C. The fracture stress, fracture strain and fracture energies were determined. The temperature development in the notch area was followed with an Infra Red camera. The cavitation of the rubber particles was studied on tensile bars with a laser setup.