Dialkyl esters of inorganic phosphoric acid (RO)2PO-OH contain only one active hydrogen atom. Hence, in accordance with the contemporary viewings, there are no theoretical limitations on the possibilities of their gas chromatographic separation. Comparison of the physicochemical properties of dialkyl- and trialkyl (characterized in more detailed extent) phosphates confirms this proposition. The evaluation of di- and trialkyl phosphates polarity by comparing the so called indices of the molecular mass, normal boiling point, and molar refraction indicates that both esters are rather low polar compounds. Nevertheless, the analyses of three reaction mixtures of phosphoric anhydride (P2O5) with excesses of 1-propanol, 2-propanol, and 1-butanol indicate the absence of dialkyl phosphates among the constituents being detected. At the same time, the impurities of the corresponding trialkyl phosphates are revealed in all cases. This can be explained by the impossibility of the gas chromatographic separation of dialkyl esters due to the following reasons: - dialkyl phosphates are rather strong acids (р К а 1.3 - 1.7); - formation of inner molecular hydrogen bonds improves the chromatographic “properties” of analytes. However, the probability of its formation in dialkyl phosphates seems to be less than those in monoalkyl esters of organic dicarboxylic acids; - esters of the phosphoric acid (including trialkyl esters) are known as the active alkylation reagents even at the elevated temperatures. This can decrease their stability during the chromatographic separation due to the possible interaction with the stationary phase of the chromatographic column. Every single factor from the ones mentioned above cannot be the principal reason of the inapplicability of the gas chromatography for the separation of dialkyl phosphates by itself. The joint action of all of them seems to be more reasonable.