Abstract: Novel tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyloxymethyl)methane having a novel crystal structure characterized by the fact that its X-ray diffraction pattern obtained by X-ray analysis using Cu-K.sub..alpha. rays shown a sharp peak at a diffraction angle 2.theta.=10.90.degree.. The above compound can be prepared by (a) transesterifying methyl or ethyl 3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate with pentaerythritol in the presence of a compound of the formula ##STR1## wherein R.sub.1 and R.sub.2 each represent an alkyl group having 1 to 6 carbon atoms,(b) treating the resulting tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyloxymethyl)methane with a lower alkanol capable of forming a molecular adduct compound therewith to convert it into the corresponding molecular adduct compound, and (c) recrystallizing the molecular adduct compound from ethanol as a solvent.