Abstract: There is disclosed a novel process for preparing products of the reaction of elemental phosphorus and elemental sulfur under reaction conditions wherein the phosphorus and sulfur are combined in a pre-mix at temperatures below the reaction temperature. The pre-mix may contain a diluent which is preferably the product of the reaction. Phosphorus pentasulfide can be prepared by heating the pre-mix to reaction temperatures wherein lower exotherm temperatures and reduced vibration are observed. Organophosphorus and thionated products can be prepared by the reaction of elemental sulfur and elemental phosphorus together with an organic compound wherein the ratio of phosphorus and sulfur generally corresponding to P.sub.2 S.sub.5. The process obviates the need for separately preparing phosphorus pentasulfide to prepare thiohated and organophosphorus compounds.