A photoinitiator blend, containinga) at least one monoacylphosphine oxide of formula I ##STR1## in which R.sup.1 denotes C.sub.1 -C.sub.18 alkyl; C.sub.1 -C.sub.4 alkyl, C.sub.5 -C.sub.8 cycloalkyl, C.sub.7 -C.sub.9 phenylalkyl, phenyl, naphthyl, biphenyl, all substituted by halogen or C.sub.1 -C.sub.6 alkoxy; phenyl, naphthyl or biphenylyl, all mono- or poly-substituted by halogen, C.sub.1 -C.sub.12 alkyl and/or C.sub.1 -C.sub.12 alkoxy; or a monovalent N--, O--, or S--containing 5-membered or 6-membered heterocyclic radical,R.sup.2 denotes phenyl, naphthyl, biphenylyl; phenyl, naphthyl or biphenylyl, all mono- or poly-substituted by halogen, C.sub.1 -C.sub.12 alkyl and/or C.sub.1 -C.sub.12 alkoxy; a monovalent N--, O--, or S--containing 5-membered or 6-membered heterocyclic radical, C.sub.1 -C.sub.18 alkoxy, phenoxy; phenoxy substituted by halogen, C.sub.1 -C.sub.4 alkyl or C.sub.1 -C.sub.4 alkoxy; benzyloxy, cyclohexyloxy or R.sup.2 and R.sup.1 form a ring together with the phosphorus atom,R.sup.3 denotes C.sub.1 -C.sub.18 alkyl; C.sub.1 -C.sub.4 alkyl, C.sub.5 -C.sub.8 cycloalkyl, C.sub.7 -C.sub.9 phenylalkyl, phenyl, naphthyl, biphenylyl, all substituted by halogen or C.sub.1 -C.sub.6 alkoxy; phenyl, naphthyl or biphenylyl, all mono- or poly-substituted by halogen, C.sub.1 -C.sub.12 alkyl and/or C.sub.1 -C.sub.12 alkoxy; a monovalent N--, O--, or S--containing 5-membered or 6-membered heterocyclic radical or a group ##STR2## in which X C.sub.2 -C.sub.8 alkene, cyclohexylene or unsubstituted or; phenylene, or biphenylene, both substituted by halogen, C.sub.1 -C.sub.4 alkyl or C.sub.1 -C.sub.4 alkoxy;b) at least one diacylphosphine oxide of formula II ##STR3## in which R.sup.4 denotes C.sub.1 -C.sub.18 alkyl; C.sub.1 -C.sub.4 alkyl, C.sub.5 -C.sub.8 cycloalkyl, C.sub.7 -C.sub.9 phenylalkyl, phenyl, naphthyl, biphenylyl, all substituted by halogen or C.sub.1 -C.sub.6 alkoxy; phenyl, naphthyl or biphenylyl, all mono- or poly-substituted by halogen, C.sub.1 -C.sub.12 alkyl and/or C.sub.1 -C.sub.12 alkoxy; a monovalent N--, O--, or S--containing 5-membered or 6-membered heterocyclic radical, C.sub.1 -C.sub.18 alkoxy, phenoxy; phenoxy substituted by halogen, C.sub.1 -C.sub.4 alkyl or C.sub.1 -C.sub.4 alkoxy; benzyloxy, cyclohexyloxy andR.sup.5 and R.sup.6 independently denote C.sub.1 -C.sub.18 alkyl; C.sub.1 -C.sub.4 alkyl, C.sub.5 -C.sub.8 cycloalkyl, C.sub.7 -C.sub.9 phenylalkyl, phenyl, naphthyl, biphenylyl, all substituted by halogen or C.sub.1 -C.sub.6 alkoxy; phenyl, naphthyl or biphenylyl, all mono- or poly-substituted by halogen, C.sub.1 -C.sub.12 alkyl and/or C.sub.1 -C.sub.12 alkoxy; a monovalent N--, O--, or S--containing 5-membered or 6-membered heterocyclic radical.