Results from adiabatic in situ coal gasification tube studies in the forward mode are presented. The reactor and the laboratory configuration are described. Combustion front channeling and the problems of operating the system adiabatically are discussed. Representative gasification data are given and several runs are analyzed for peak combustion, temperature, combustion and devolatization front velocities and production gas flow rate, composition, and heating value. All results are made viable through completion of material and energy balances on the system and radial conductive heat losses are determined. The laboratory results are correlated with the Hanna field tests and with a one-dimensional in situ coal gasification numerical model.