The paper presents a new procedure for assessing the polarity and hydrophobicity of deep eutectic solvents (DESs) based on the measurement of the DES contact angle on glass. DESs consisting of benzoic acid derivatives and quaternary ammonium chlorides – tetrabutylammonium chloride (TBAC) and benzyldimethylhexadecylammonium chloride (16-BAC) in selected mole ratios were chosen for the study. To investigate the DESs polarity, an optical goniometer and an ET(30) solvatochromic scale based on the Reichardt’s dye were used. The research demonstrated the high accuracy and precision of the developed procedure. The simplicity of the examination and the availability of basic equipment allow the implementation of the developed procedure in routine investigations of DESs.