The objective of the research project was to assess the impact of culturing parameters and medium composition on the capability of halophilic microorganisms to denitrify brines. Haloferax denitrificans archaeon were used for the denitrification process. Optimal temperature and pH values as well as NaCl concentrations were determined for the examined bacteria. Experiments were carried out according to the Latin square design. The performed investigations consisted in the selection of the medium which was to guarantee good conditions for the growth and denitrification for the examined bacteria. This medium differed from those employed for the non-halophilic denitrification bacteria and that is why it was necessary to supply the media with macroclements in the form of potassium (I), magnesium (II), and calcium (II) ions as well as such microelements as molybdenum (VI), iron (II), and copper (II). The above-mentioned components helped halophilic microorgansms survive in unfavourable environmental conditions characterised by a high osmotic potential. Methanol was selected as the carbon source for the denitrification and, in addition, the medium was supplemented with 250 mg dm(-3) yeast extract which provided the experimental halophilic archaeon with a rich source of amino acids and active substances essential for their growth and development. (c) 2006 Elsevier Inc. All rights reserved.