A biosensor for phosphate determination with the flow-injection system was developed using rhodium nanoparticles modified Poly(pyrrole-co-[1-(2-aminophenyl) pyrrole])/pyruvate oxidase. The biosensor showed a very wide linearity up to 70 mM phosphate concentration compared to previously reports, response time of 4 s., operational stability with a relative standard deviation of 0.009 % and accuracy of 99.4 %+/- 0.949 at a flow rate of 2.0 Ml min.(-1) at exactly -0.68 V. Detection limit were calculated to be 21 +/- 0.001 mu M by preserving 81.1 % of its initial response at the end of 16(th) days. Artificial urine was analyzed without dilution to investigate biosensor performance.