Abstract The molecular and crystal structure and the hydrogen bonding in crystal and in solutions of N-phenyl-N-(3, 5-di-tert-butyl-4-hydroxybenzyl) thiourea and N-(3, 5-di-tert-butyl- 4-hydroxybenzyl) thiourea were studied by single crystal X-ray diffraction and IR spectroscopy. The intermolecular interactions of these compounds are essentially different.