The present invention is concerned with a process and a plant for the production of sulphuric acid wherein a sulphur dioxide-containing feed gas is converted, at least in part, with oxygen in at least two contact stages of main contacts arranged in series, to generate sulphur trioxide, and wherein generated sulphur trioxide-containing gas is conducted to an absorber and converted therein to sulphuric acid. In order to be able to economically process feed gases of a sulphur dioxide content of between 13 and 66% by volume to sulphuric acid, using conventional catalysts, it is suggested to withdraw from a contact stage connected upstream of the last main contact stage, a partial stream of the sulphur dioxide- and sulphur trioxide-containing gas, to mix the said partial stream with the feed gas to generate a contact gas of a sulphur dioxide content of more than 13% by volume, and to return the same to the first contact stage.