The objective of the research study was to assess the effect of some selected conditions and additional substances used in the production of meat batters on reducing sodium nitrate (III) by Staphylococcus carnosus obtained from an industrial vaccine developed to be used in the production of fermented meat products (Bactoferm S-B-61). The study was conducted in a model system, i.e. a TBS liquid protein medium. The bacterial culture was reproduced on a TSB liquid protein medium for 20 h, at 30 ºC. In the individual experiments, there were used bacteria from the third passage. The effect was investigated of S. carnosus on reducing sodium nitrate(III) under certain conditions (time, temperature, and initial number of bacteria). Sodium chloride and polyphosphates were added as additional substances. In every experiment, before and after incubation, there were determined nitrate(III) and nitrate(V), S. carnosus, pH, and redox potential. The experiments were performed in three parallel repeats. Based on the analyses performed, it was found that the strain of Staphylococcus carnosus bacteria reduced sodium nitrate at temperatures between 20 and 40 ºC. The increase in the initial number of bacteria to 10⁷ cfu/cm³ significantly affected the reduction of nitrate(III). It was reported that along with the increase in the number of bacteria, the acidity degree of the protein medium increased, whereas the redox potential of the model system decreased. Sodium chloride and polyphosphates had an inhibiting effect on the growth and bacterial activities within the reduction range of sodium nitrate(III). It was found that the strain of S. carnosus bacteria reduced sodium nitrate(III) but only under certain environmental conditions.