The function of the reference electrode is to complete the pH measurement circuit, in conjunction with pH sensor. This paper described the characterization of in-house Reference Electrode (RE) using green colour electrolyte as a medium. The in-house RE was tested with few subjects such as commercial RE, in-house Nitrate Sensor, and in-house pH sensor. The study is focusing on the effect and stability of colour electrolyte using in RE. The result shows In-house reference electrode with coloured electrolyte performed a very stable output. Total of 3 experiment done shows the RE are able to detect different pH (buffer solution) and provide a good slope R-2 near to 1. Furthermore, the field testing shows the colour electrolyte able to improve the voltage reading and minimize drift effect.