AbstractAn improved method of isolation of betulin and lupeol from birch bark is developed and reported. The method afforded triterpenes with purity of 98.2% (betulin) and 96.3% (lupeol), respectively. Chromyl chloride was also investigated as an oxidating agent of O-acetylated betulin and lupeol. The transformation of isopropenyl moiety to aldehyde group was observed. Graphical abstract