The present invention provides a process for the manufacture of a useful product from carbonaceous feedstock of fluctuating compositional characteristics, the process comprising the steps of: continuously providing the carbonaceous feedstock of fluctuating compositional characteristics to a gasification zone; gasifying the carbonaceous feedstock in the gasification zone to obtain raw synthesis gas; recovering at least part of the raw synthesis gas from the gasification zone and supplying at least part of the recovered raw synthesis gas to a partial oxidation zone; equilibrating the H2:CO ratio of the raw synthesis gas in the partial oxidation zone to obtain equilibrated synthesis gas; recovering at least part of the equilibrated synthesis gas from the partial oxidation zone and treating the gas to remove impurities and generate a fine synthesis gas; optionally adjusting the H2:CO ratio of at least part of the fine synthesis gas to obtain adjusted fine synthesis gas; and converting the optionally adjusted fine synthesis gas into the useful product in a further chemical reaction requiring a usage ratio; wherein the fine synthesis gas H2:CO ratio is below the usage ratio and wherein any optional adjustment of at least part of the fine synthesis gas H2:CO ratio is effective to increase the H2:CO ratio in the fine synthesis gas to a level at, nearer to or above the usage ratio; wherein the H2:CO ratio of the raw synthesis gas fluctuates during operation of the process as a result of the fluctuating compositional characteristics of the carbonaceous feedstock by a percentage of ±x; and the H2:CO ratio of the equilibrated synthesis gas does not fluctuate during operation of the process or fluctuates during operation of the process as a result of the fluctuating compositional characteristics of the carbonaceous feedstock by a percentage ±y, y being a lower percentage than x.