Composition of a polymeric potential-determining phase for the ibuprofen selective electrode was determined. The different possibilities of using various quaternary ammonium salts -dimethyldidecylammonium bromide, methyltrioctylammonium. chloride, tetraoctylammonium chloride and methyltrioctyloammonium 2-(4-isobuthylphenyl) priopionate - as anion exchangers in polymer membranes of ibuprofen electrodes were examined. The following basic electrode parameters were investigated: measurement range, slope, limit of detection, lifetime, dependence of the electrode potential on pH and selectivity coefficients in relation to some organic and inorganic anions.