A rigid or semi-rigid polyurethane or polyisocyanurate foam, coating, adhesive or elastomer comprising a hydroxyl-functional phospholene-1-oxide compound of the formula (I): wherein: the dashed line indicates a double bond located between the carbon atom at position 3 and one of the carbon atoms at positions 2 and 4, provided that each of the two ring carbon atoms which are not part of the double bond are each bonded to one of the two hydrogen atoms shown in the structural formula (I-A); R 1 , R 2 , R 3 and R 4 are independently selected from H, a linear or branched alkyl group containing from 1 to 4 carbon atoms, or chlorine; and, X is either and when X is ------(Z) k -R 7 , Z is -(Y-O) n -, wherein Y is a linear or branched alkylene group containing from 2 to 8 carbon atoms and n represents an integer from 1 to 20; k may be 0 or 1; R 7 is selected from hydrogen, a hydroxy-terminated linear or branched alkylene group containing from 2 to about 8 carbon atoms; and, provided that when k is zero, R 7 is the hydroxy-terminated linear or branched alkylene group and when k is 1, R 7 is hydrogen, and when X is R 5 and R 6 are each independently selected from H, a linear or branched alkyl group containing from 1 to 8 carbon atoms, a linear or branched alkenyl group containing from 2 to 8 carbon atoms, a hydroxyalkyl group containing from 2 to 4 carbon atoms, a halo-substituted alkyl group containing from 1 to 8 carbon atoms, an alkoxy group containing from 1 to 8 carbon atoms, an aryl group containing from 6 to 12 carbon atoms and an alkylaryl group containing from 7 to 16 carbon atoms, or R 5 and R 6 are bonded to each other to form a cycloalkyl group containing from 5 to about 8 carbon atoms. the dashed line indicates a double bond located between the carbon atom at position 3 and one of the carbon atoms at positions 2 and 4, provided that each of the two ring carbon atoms which are not part of the double bond are each bonded to one of the two hydrogen atoms shown in the structural formula (I-A); R 1 , R 2 , R 3 and R 4 are independently selected from H, a linear or branched alkyl group containing from 1 to 4 carbon atoms, or chlorine; and, X is either and when X is ------(Z) k -R 7 , Z is -(Y-O) n -, wherein Y is a linear or branched alkylene group containing from 2 to 8 carbon atoms and n represents an integer from 1 to 20; k may be 0 or 1; R 7 is selected from hydrogen, a hydroxy-terminated linear or branched alkylene group containing from 2 to about 8 carbon atoms; and, provided that when k is zero, R 7 is the hydroxy-terminated linear or branched alkylene group and when k is 1, R 7 is hydrogen, and when X is R 5 and R 6 are each independently selected from H, a linear or branched alkyl group containing from 1 to 8 carbon atoms, a linear or branched alkenyl group containing from 2 to 8 carbon atoms, a hydroxyalkyl group containing from 2 to 4 carbon atoms, a halo-substituted alkyl group containing from 1 to 8 carbon atoms, an alkoxy group containing from 1 to 8 carbon atoms, an aryl group containing from 6 to 12 carbon atoms and an alkylaryl group containing from 7 to 16 carbon atoms, or R 5 and R 6 are bonded to each other to form a cycloalkyl group containing from 5 to about 8 carbon atoms. <EOS>