We analyse the five most common ovens that manufactured coal gas and their implementation in gasworks in Spain. This implementation was divided into five periods according to the degree of development. Data are based on technical statistics, and on documents obtained from gas companies. The statistics were compiled in the 1940s by the Francoist Trade Union of water, gas and electricity. The documents were obtained from the archive of the Gas Natural Foundation in Barcelona. Although we cannot determine the entire evolution, it is possible to obtain a rough idea of the period during which coal was used as a raw material.