The present invention discloses an integrated process and an apparatus for production of various alcohols and Oligomerization of Olefinic feed stocks comprising butylenes and mixture thereof. In this process the combined light olefinic hydrocarbon feedstock is divided into two streams and contacted in two different reaction zones, viz. hydration and oligomerization. The mixture of alcohols and oligomer product from hydration reaction is separated and the bottom stream from separator is routed to oligomerization reaction zone in a controlled quantity as selectivity enhancer. Both the reaction zones are operated at different conditions. The product from oligomerization zone is further separated in to lighter and heavier components. Each reaction zone may comprise series of reactors filled with acidic catalysts comprising ion exchange resins.