The potential oxygen flux density in soil is one of the parameters describing the availability of oxygen for plant roots. The parameter can be estimated with the help of two electrochemical methods - the amperometric method and the voltammetric method. The primary objective of this work was to improve the voltammetric method for the determination of the potential oxygen flux density in soil through the estimation of the selectivity of the method and of the possibility of the application of the two-electrode symmetrical measuring setup. Attainment of the objective was possible due to the realization of the successive stages of the study: 1) validation of the thesis that oxygen reduction is the sole source of electric current flow in the measuring setup; 2) selection of proper measurement procedure in the aspect of maximizing the repeatability of results obtained for a given soil sample; 3) comparison of measurements of the potential oxygen flux density taken with a three-electrode potentiostat-system setup and a two-electrode symmetrical setup. 4) investigation of the effect of the selection of integration range in the voltammetric method for the estimation of potential oxygen flux density in soil on the level of uncertainty of the results obtained. An additional objective was validation of the thesis that the current-voltage characteristics recorded during the measurements of the potential oxygen flux density in saturated soil may provide a basis for the estimation of salinity as expressed by the electric conductivity of soil solution. Summarizing the results of the study one can state that: • the proposed method of measurement and interpretation of results constitutes an improvement of the voltammetric method for the estimation of the potential oxygen flux in soil by reducing the measurement uncertainty and providing a deeper-than-hitherto assessment of the uncertainty and factors affecting the uncertainty. Many of the results obtained may also help improve the amperometric method; • voltammetric measurements of the potential oxygen flux in soil can be conducted with the help of a two-electrode symmetrical measuring setup (with both electrodes made of platinum), which permits the elimination of measurement environment disturbance due to soil compaction with the relatively large saturated calomel electrode, the avoidance of technical difficulties involved in the installation of the electrode encased in a glass casing, especially in compacted soils, and undertaking further work on the development of an integrated probe for the measurement of soil moisture with the TDR technique and of soil oxygenation with the voltarnmetric method; • the value of background current which results from the reduction of substances other than oxygen in the course of measurements with both the methods under anaerobic conditions may be approximately twice the value in "chemically pure" solution of potassium chloride. At the same time, the value of measurement error decreases with increasing oxygenation and may be up to 20% of the value determined in amperometric measurements and up to 10% in voltammetric measurements. These values should be taken into account in the method uncertainty budget; • the uncertainty of soil potential oxygen flux density determination with the voltammetric method can be minimized through the adoption, for the integration, of the current-voltage relations of the generalized integration range. One of the methods for the determination of the limits of the range can be the averaging of the upper and lower limits of quasi plateau area determined individually for each measurement; • the platinum electrode which acts as the measuring electrode should be re-installed before each successive measurement. This procedure will allow the electrode to be cleaned of residues from the preceding measurement that might block the electrode for the next measurement; • the current-voltage characteristics recorded in the course of the voltammetric measurements of the potential oxygen flux in saturated soils may be interpreted in terms of soil salinity (as expressed by electric conductivity); • the analogue electrical model of phenomena taking place during the electrochemical estimation of potential oxygen flux in soil may be used as a tool for the validation of measurement apparatus.