The gasification rate was measured of chunks of coal with a high content of volatiles, average size of 65 x 47 X 38 mm and an initial weight of 120 +/- 7 g. The influence of air temperature and velocity on the gasification rate was studied in a tubular experimental device. The time dependencies of the gasification rate and some gaseous species on air temperature and velocity were observed. A discontinuity appeared during gasification, which is not apparent on burning small coal pieces or coal dust.