In this research, the capability of functioning iridium, ruthenium and titanium oxides together in pH sensing application as tri-system has been emphasized. The corporation between such oxides has improved the own drawbacks which represented in existence of different states of oxides in the case of IrO and effectiveness of alkaline solution in the RuO case. Sol-gel method supported by new economic environment-friendly spray coating used to coat wire substrates titanium and stainless steel. A new method created to evaluate the spray coating. SEM of the microstructure of the sensitive layer provides a fine-grained and homogenous with sandy shape grains and significant porosity, with thickness 1.9-1.5 mu m for titanium and stainless steel substrates correspondingly. The sensors stability tested over an extended period 1-120 days the sensitivity remains 59 mV/pH as provided by the electrodes. Fast response estimated as 4-8 s, reversibility concerning insignificant hysteresis ranged from -1 to 3 mV, perfect temperature dependency obtained and negligible selectivity for K+, Na+, Li+ and Mg2+ has been detected.