Recurrent approximation of analytes’ net retention times ( t R) in reversed phase high performance liquid chromatography (RP HPLC) at different contents of organic constituent in the eluent ( C ) is recommended as a method of revealing the reversible hydrate formation. The criterion of that are the deviations of the dependences t R( С + D С ) = at R( С ) + b (*) from linearity, where D С is the constant increment of concentration variations; in our case D С = 5%. However, such deviations are rather small and, hence their measuring requires high robustness of the equipment involved. Besides hydrate formation, there are additional reasons for deviations, namely discrepancies between the real and the selected flows of the eluent. Comparing t R values obtained for the same analytes using the same chromatographic column at the same conditions, but with different HPLC instruments using the systems methanol - water as the eluent confirms that t R values of one data set are equal only to approx. 76-98% t R values of another data set. Therefore, the eluent flow in the second case exceeds that in the first regime at the same proportion. The simple method for revealing such flow deviations is proposed. It is based on the recurrent approximation of t R = f ( C ) data sets for any compounds forming no hydrates in RP HPLC conditions (chlorobenzene was selected). The absence of the influence of any distorted factors is confirmed with values of correlation coefficients for recurrent dependencies (*) exceeding 0.999.