Abstract: The invention relates to a process for producing a product gas mixture containing hydrogen-containing chlorosilanes within an integrated process by hydrogenating integrated process by-product silicon tetrachloride and organochlorosilane, more particularly methyltrichlorosilane, with hydrogen in a pressurized hydrogenation reactor comprising one or more reaction spaces each consisting of a reactor tube of gastight ceramic material, wherein the product gas mixture is worked up and at least a portion of at least one product of the product gas mixture is used as starting material for the hydrogenation or as starting material for some other process within the integrated process. The invention further relates to an integrated system useful for practising the integrated process.