The use of pyroelectric calorimeters for pulsed measurements of the thermal diffusivity of thin films is described. The material under study is directly coated on to a pyroelectric calorimeter. A transient heat source is generated at the surface of the sample via absorption of a laser pulse. By analysis of the transmitted heat pulse, the thermal diffusivity of the sample can be determined. The potentials of this method are demonstrated on polymer films with thicknesses in the submicrometer range.