Abstract: A process is provided for the manufacture of ferric sulphate compounds from ferrous sulphate in a closed vessel containing a liquid phase and a vapor phase, the process comprising the oxidation of Fe.sup.++ to Fe.sup.+++ under pressure utilizing commercial oxygen in the closed vessel using NOx as a catalyst where x is a number between 1 and 2 inclusive of 1 and 2 and wherein the process comprises the following reactions: ##EQU1## wherein n is any integer greater than or equal to two (2) and y is any integer which is equal to, or greater than zero (0) and less than 3n and wherein the oxidation of Fe.sup.++ is affected by spraying the liquid phase including a solution containing Fe.sup.++ introduced to the closed vessel, through a reacting cloud comprising NO, NO.sub.2 and O.sub.2 enclosed in the vapor space of the closed vessel and wherein substantially only Ferric ions is present in the liquid phase in the closed vessel relative to the amounts of Ferric and Ferrous ions prior to the addition of FeSO.sub.4.