In this research work, we have used the image processing technique for determining the end of sodiumsulphate with standard barium chloride in precipitation titration. The white precipitate of barium sulphateproduced by the reaction of barium chloride and sodium sulphate was dispersed in deionized water bymagnetic stirrer and its images were taken by mobile phone camera. The resulting pictures were analyzed byPhotoshop Software which shows that the intensity of magenta colour has maximum sensitivity by changingthe mass of barium sulphate. Therefore; magenta colour was selected as the optimum colour. Also, to depictthe calibration curve of sulphate anion, different concentrations of sulphate were prepared in bufferedsolutions and by addition of barium chloride to them, the intensity of magenta colour was calculated. Theresults show that the calibration curve was linear in the range of 5-75 mg.L-1 of sulpahte with a correlationcoefficient of 0.973. Finally, by titration of different real samples such as Tap, river and mineral waterscontaining sulphate anion with standard barium chloride, the variation of magenta colour was recorded andthe concentration of sulpahte anion was determined.