A drop-weight instrument is described to investigate the impact sensitivity of high explosives at elevated temperatures. This test is typically performed to discover potential safety aspects of either newly synthesized materials of unknown behavior. Normally, drop-weight impact sensitivity tests are conducted at room temperature, since high explosives are often stored or handled at room temperature. The instrument described here has the capability of heating the samples from ambient to 300 degrees C prior to impact. The thermal impact sensitivities of PETN, TATP, HMX, and silver azide (AgN(3)) as a function of temperature are obtained. The phase transition of HMX can clearly be observed by a significant decrease in the impact height in situ.