ESR spectra of x-irradiated single crystals of (C6H5)3AsO were investigated. One of the two radical species trapped in the crystal was identified as being the diphenylarsino radical (C₆H₅)₂As. The g and ⁷⁵As magnetic coupling tensors were determined together with the ⁷⁵As quadrupole interaction tensor. These ESR parameters are shown to be consistent with a bond angle CAsC of 98°±2°. The spectra parameters of (C₆H₅)₂As are compared with those of (C₆H₅)₂P and NH₂.