In the hazardous waste community, the term 'thermal destruction' is a catch-all phrase that broadly refers to high temperature destruction of hazardous contaminants. Included in the thermal destruction category are treatment technologies such as rotary kiln incineration, fluidized bed incineration, infrared thermal treatment, wet air oxidation, pyrolytic incineration, and vitrification. Among them, conventional rotary kiln incineration is the most established, having been a disposal method for many years, and therefore often serves as a barometer by which the relative success of similar technologies may be gauged. Public sentiment on environmental issues and increasingly stringent environmental regulations has, over time, spurred the design and development of innovative thermal treatment processes that are directed at reducing harmful emissions and residuals that may require further treatment or disposal. In-situ vitrification (ISV), a technology that combines heat and immobilization, is one such innovative and relatively new technology. The paper presents a comprehensive overview of ISV as compared with rotary kiln incineration in the areas of process performance, process residuals, process limitations, applicable or relevant and appropriate (ARARs) regulations, criteria and limitations, and costs. (Copyright (c) 1991--Air and Waste Management Association.)