Abstract: Ultrafine MnO₂ powders were used to fabricate two kinds of solid pH electrodes. The electrode coated with a thin film of MnO₂ could exhibit a fast,stable pH-response in aqueous solution. A linear pH-potential curve was observed over the range of pH 2～12 with a sensitivity of -81.5 mV/pH at room temperature. However,the electrode fabricated with screen-printed method had a little poor than the coated electrode.