Tertiary-aliphatic alpha-peroxyazo compounds represented by the structure ##STR1## processes for preparing these compounds by reacting ##STR2## with salts or salt solutions of HOOH (III), (r").sub.3 cooh (iv), ##STR3## and the use of these novel compounds as polymerization initiators for vinyl monomers and as curing agents for resins. For example, 2-t-butylazo-2-(t-butylperoxy)-propane is prepared by reacting the potassium salt of t-butyl-hydroperoxide with 2-t-butylazo-2-chloropropane; and the product is used to cure unsaturated polyester resin at room temperature and to polymerize vinyl chloride at 20.degree.-30.degree. C.