Ultrasonic irradiation resulting in acoustic cavitation was employed during the partial crystallization of diphenyl oxide and dimethyl phenyl carbinol from their respective crude melts. The crystals obtained showed improved purity and better olefactory values for both compounds. This was confirmed by melting point measurements and image analysis of the crystals thus obtained. The beneficial effect of ultrasonic irradiation on the resultant properties is explained on the basis of the theory of acoustic cavitation.