Process for photocuring photopolymerizable compositions, which process comprises: I) preparing a photopolymerizable composition comprising: a) from 50 to 99.9% by weight of at least one ethylenically unsaturated compound; b) from 0.1 to 35% by weight of at least one 3-ketocoumarine of formula I: in which: R 1 is a substituted or unsubstituted C 2 -C 12 alkyl group; Cou is a coumarine group of formula: wherein: R 2, R 3, R 4 and R 5 are, independently of one another, hydrogen; or -S-R 7, where R 7 is hydrogen, C 1 -C 12 alkyl, C 3 -C 12 alkenyl, substituted or unsubstituted phenyl, aryl or heteroaryl, C 5 -C 6 cycloalkyl, C 1 -C 12 alkyl which is substituted with SH, -N(C 1 -C 6 alkyl) 2, piperidino, morpholino, piperazino, -OH, -O(C 1 -C 12 alkyl), -COOH; or C 1 -C 12 alkoxy; R 6 is hydrogen, a hydroxyl group, an alkyl group having from 1 to 4 carbon atoms; or Cou is a substituted or unsubstituted naphtho-coumarine group of formula: provided that at least one of R 2, R 3, R 4 and R 5 is different from H and that, when Cou is (a) and at least one of R 2, R 3, R 4 and R 5 is C 1 -C 12 alkoxy or when Cou is (b), (c) or (d), R 1 is a substituted or unsubstituted C 1 -C 12 alkyl group; II) photopolimerizing the photopolymerizable composition so obtained with a LED light source emitting at wavelengths comprised between 365 nm and 420 nm. I) preparing a photopolymerizable composition comprising: a) from 50 to 99.9% by weight of at least one ethylenically unsaturated compound; b) from 0.1 to 35% by weight of at least one 3-ketocoumarine of formula I: in which: R 1 is a substituted or unsubstituted C 2 -C 12 alkyl group; Cou is a coumarine group of formula: wherein: R 2, R 3, R 4 and R 5 are, independently of one another, hydrogen; or -S-R 7, where R 7 is hydrogen, C 1 -C 12 alkyl, C 3 -C 12 alkenyl, substituted or unsubstituted phenyl, aryl or heteroaryl, C 5 -C 6 cycloalkyl, C 1 -C 12 alkyl which is substituted with SH, -N(C 1 -C 6 alkyl) 2, piperidino, morpholino, piperazino, -OH, -O(C 1 -C 12 alkyl), -COOH; or C 1 -C 12 alkoxy; R 6 is hydrogen, a hydroxyl group, an alkyl group having from 1 to 4 carbon atoms; or Cou is a substituted or unsubstituted naphtho-coumarine group of formula: provided that at least one of R 2, R 3, R 4 and R 5 is different from H and that, when Cou is (a) and at least one of R 2, R 3, R 4 and R 5 is C 1 -C 12 alkoxy or when Cou is (b), (c) or (d), R 1 is a substituted or unsubstituted C 1 -C 12 alkyl group; a) from 50 to 99.9% by weight of at least one ethylenically unsaturated compound; b) from 0.1 to 35% by weight of at least one 3-ketocoumarine of formula I: in which: R 1 is a substituted or unsubstituted C 2 -C 12 alkyl group; Cou is a coumarine group of formula: wherein: R 2, R 3, R 4 and R 5 are, independently of one another, hydrogen; or -S-R 7, where R 7 is hydrogen, C 1 -C 12 alkyl, C 3 -C 12 alkenyl, substituted or unsubstituted phenyl, aryl or heteroaryl, C 5 -C 6 cycloalkyl, C 1 -C 12 alkyl which is substituted with SH, -N(C 1 -C 6 alkyl) 2, piperidino, morpholino, piperazino, -OH, -O(C 1 -C 12 alkyl), -COOH; or C 1 -C 12 alkoxy; R 6 is hydrogen, a hydroxyl group, an alkyl group having from 1 to 4 carbon atoms; or Cou is a substituted or unsubstituted naphtho-coumarine group of formula: provided that at least one of R 2, R 3, R 4 and R 5 is different from H and that, when Cou is (a) and at least one of R 2, R 3, R 4 and R 5 is C 1 -C 12 alkoxy or when Cou is (b), (c) or (d), R 1 is a substituted or unsubstituted C 1 -C 12 alkyl group; R 1 is a substituted or unsubstituted C 2 -C 12 alkyl group; Cou is a coumarine group of formula: wherein: R 2, R 3, R 4 and R 5 are, independently of one another, hydrogen; or -S-R 7, where R 7 is hydrogen, C 1 -C 12 alkyl, C 3 -C 12 alkenyl, substituted or unsubstituted phenyl, aryl or heteroaryl, C 5 -C 6 cycloalkyl, C 1 -C 12 alkyl which is substituted with SH, -N(C 1 -C 6 alkyl) 2, piperidino, morpholino, piperazino, -OH, -O(C 1 -C 12 alkyl), -COOH; or C 1 -C 12 alkoxy; R 6 is hydrogen, a hydroxyl group, an alkyl group having from 1 to 4 carbon atoms; R 2, R 3, R 4 and R 5 are, independently of one another, hydrogen; or -S-R 7, where R 7 is hydrogen, C 1 -C 12 alkyl, C 3 -C 12 alkenyl, substituted or unsubstituted phenyl, aryl or heteroaryl, C 5 -C 6 cycloalkyl, C 1 -C 12 alkyl which is substituted with SH, -N(C 1 -C 6 alkyl) 2, piperidino, morpholino, piperazino, -OH, -O(C 1 -C 12 alkyl), -COOH; or C 1 -C 12 alkoxy; R 6 is hydrogen, a hydroxyl group, an alkyl group having from 1 to 4 carbon atoms; or Cou is a substituted or unsubstituted naphtho-coumarine group of formula: provided that at least one of R 2, R 3, R 4 and R 5 is different from H and that, when Cou is (a) and at least one of R 2, R 3, R 4 and R 5 is C 1 -C 12 alkoxy or when Cou is (b), (c) or (d), R 1 is a substituted or unsubstituted C 1 -C 12 alkyl group; II) photopolimerizing the photopolymerizable composition so obtained with a LED light source emitting at wavelengths comprised between 365 nm and 420 nm.