The decision to include a description of the methods used for processing BOD data obtained in long-term experiments appeared after some articles by Gotovtsev A. V., where it was suggested to calculate kinetic constants from BOD measurements on two dates (over exposure time t and 2t) without taking into account the multistage development (characteristic for the BOD process). The basic information is about the mechanism of the process obtained by summarizing the results of hydrochemical and microbiological studies of the BOD process is considered. The possibilities of estimating BOD kinetic parameters are shown by analyzing 126 days long experiments with water samples taken from different water bodies of Karelia in different seasons of the year at 10 and 20 °C. Having processed 33 experiments we revealed four types of multistage BOD-curves: EL – exponential-linear, AL – autocatalytic-linear, EAL – exponential-autocatalytic-linear, and AAL – poly-autocatalytic-linear. BOD stage I developed in the first 14–25 days of the experiments, stage II was observed in 1/3 of the experiments on the 30th–60th days, and the stationary (or linear) BOD stage was recorded in all the experiments. The obtained values of the BOD kinetic parameters estimated using the results of individual experiments and averaged over the entire set of activities for individual stages, water sampling seasons and exposure modes are presented and discussed. A dependence on the exposure temperature of water samples was found for the BOD kinetic parameters [О2]I (BOD threshold values at stage I), v1 and ωs (BOD rates at stage I and linear stage, respectively). The possibilities of using the values of kinetic parameter for estimating BOD rates at water temperatures in situ under natural conditions are demonstrated.