The pyrolysis and coking of samples of Athabasca bitumen and its pentane-insoluble fraction were observed under rapid heating conditions. Samples were suspended on a thin rod and heated with radiant heaters under vacuum. Images were recorded using a CCD camera system. Samples were heated for 2 s to give inside temperatures as high as 673 K in a 1 mm droplet. The heating rates at the exterior surface of the samples exceeded 680 K/s. Important variables included the composition, shape, and size of the sample. Temperature measurements depended on the location of the thermocouple in the sample and the size of the thermocouple. The observations showed that the Liquid phase rapidly evolved a cloud of vapor, which was bright and luminous under the radiant heaters. The rate of formation and expansion of the cloud depended on the volatile content of the sample. The samples were liquid under the observation conditions, but even under vacuum, the liquid did not foam or froth significantly once vapor evolution had begun. These observations suggest that pyrolysis and coking of liquid droplets and films can be modeled using the simple geometry of the liquid phase, rather than expanded vapor-liquid foams.