Gregory Smith, has investigated the chemical kinetics of combustion, the atmosphere, and other gas phase processes. His work includes the development and application of optical techniques such as laser induced fluorescence to species measurements in flames and to specific reaction rate determinations.

Smith also specializes in theoretical methods to extrapolate or estimate reaction rates, and modeling of processes to establish quantitative links between observations or outcomes, and chemical reactions and uncertainties. This has included a collaboration to develop the widely used, optimized GRIMech mechanism for natural gas combustion.

Smith was named an SRI Fellow in 2003.