Essential difference between the underground gasification and the gasification of coal in gas generators is discussed. Experiments on underground gasification of coal in surface laboratory gas generators are justified. Experiments carried out in those generators are described. A method was worked out for the analysis of the processes allowing a seperate calculation of products deriving from degasification and gasification of coal, as those processes are running jointly during the underground gasification of coal. The analysis also allows the calculation of parameters essential for the whole process. The results and conclusions drawn from the experiments carried out are discussed. The importance and the role of certain parameters in the process of gasification are presented as well as the conditions under which the gas of a relatively high calorific value is to be obtained in a continuous way. Lower and upper limits of the normal flowing speed of oxygen per unity of surface of the coal block front.