Abstract: The present invention relates to a process for isolating soluble dietary fibers and valuable polyphenols from olive mill wastewater, wherein the olive mill wastewater is defatted by removing the fat by centrifugation and concentrated by removing the water content. The defatted and dehydrated mixture is extracted using ethanol and an organic acid and the dietary fibers are separated from the polyphenols by precipitation of the dietary fibers in ethanol. This alcoholic residual is rich in polyphenols, known as anti-oxidants can be used as a healthy and tasty additive to drinks. The soluble dietary fibers are further separated from the insoluble dietary fibers by redissolving the precipitated dietary fibers into water whereby the insoluble dietary fibers precipitate leaving the soluble dietary fibers in solution. The soluble fibres from OMW can be used as an additive and/or a fat replacer in other food items.