An integrated process for the production of a useful liquid hydrocarbon product comprises: feeding a gasification zone with an oxygen-containing feed and a first carbonaceous feedstock comprising waste materials and/or biomass, gasifying the first carbonaceous feedstock in the gasification zone to produce first synthesis gas, partially oxidising the first synthesis gas in a partial oxidation zone to generate partially oxidised synthesis gas, combining at least a portion of the first synthesis gas and/or the partially oxidised synthesis gas and at least a portion of electrolysis hydrogen obtained from an electrolyser in an amount to achieve the desired hydrogen to carbon monoxide molar ratio of from about 1.5:1 to about 2.5:1, and to generate a blended synthesis gas, wherein the electrolyser operates using green electricity; and subjecting at least a portion of the blended synthesis gas to a conversion process effective to produce the liquid hydrocarbon product.