Abstract: Stabilized peroxygen containing compositions are disclosed, both in thickened viscous form and in dry form. The compositions contain newly synthesized calcium sulfate crystals that function as a thickener and stabilizing agent against metal-catalyzed decomposition. The invention discloses a composition comprising 0.5 wt % to 50% wt of hydrogen peroxide. 2.0 wt % to 80.0% wt of newly synthesized calcium sulfate crystals, being of individual sheet or needle shape, and water, said composition having a viscosity of 200 cP to 20,000 cP. The invention further provides a process for making same, comprising the reaction of a water soluble calcium containing salt with sulfuric acid or a salt thereof in an aqueous hydrogen peroxide solution at a reaction temperature of up to 80 C in a mixing apparatus, followed by a concentration step in order to thicken into a stable viscous dispersion or paste containing at least 2 wt % and preferably 10 wt % to 15 wt % of CaSO4.