Leuco dyes of the formula (I) are disclosed, ##STR1## wherein R.sub.1, R.sub.2, R.sub.3 and R.sub.4 each represent an alkyl group having 1 to 10 carbon atoms; X represents hydrogen, an alkyl group having 1 to 10 carbon atoms, an alkoxyl group having 1 to 10 carbon atoms or a halogen; and Y represents R.sub.5 --Z--SO.sub.2 NH--, R.sub.6 --Z--CONH--, or ##STR2## in which Z represents ##STR3## R.sub.5 and R.sub.6 each represent hydrogen, an alkyl group having 1 to 10 carbon atoms, or a halogen; and R.sub.7 and R.sub.8 each represent hydrogen, provided that both R.sub.7 and R.sub.8 may not be hydrogen, a cyano group, or --COR.sub.9, in which R.sub.9 represents a lower alkyl group, a lower alkoxyl group, a phenyl group which may be substituted by an alkyl group having 1 to 4 carbon atoms, an alkoxyl group having 1 to 4 carbon atoms, or a halogen; a naphthyl group which may be substituted by an alkyl group having 1 to 4 carbon atoms, an alkoxyl group having 1 to 4 carbon atoms or a halogen. Further a recording material comprising any of the above-mentioned leuco dyes and a particular phenolic compound as a color developer capable of inducing color formation in the leuco dye is disclosed.