Abstract: A process for the in situ gasification of shale avoids the necessity of initially fracturing the shale bed and includes the placement of a gas-fired heater assembly within a bore hole followed by the application, from above ground, of fuel gas and combustion air, both of which are regulated to maintain an initial start-up temperature of over 1000 degrees F. and thereafter a constant temperature of below 1500 degrees F. throughout a reaction zone formed in the surrounding shale bed. Specifically, a production temperature of 1200 degrees F. has been found most desirable. By maintenance of this temperature, voids created in the reaction zone as kerogen is retorted to evolve natural gas, become black body radiators assisting to insure a sustained, constant high volume extraction of natural gas having a BTU value of over 800 and devoid of any liuqids.