Previous studies have shown the possibility of colorimetrically determining hydrogen peroxide by its reaction with titanium oxysulfate, to give an orange-coloured complex (absorbance maxima = 410 nm). In this present investigation, we show the possibility of using this approach to quantify hydrogen peroxide using the camera of a smartphone to record images of the orange colour developed. The Red, Green, and Blue (RGB) colour numerical components of this image were obtained by the use of a downloadable free App. The RGB values obtained directly showed poor R² values and detection limits resulting from interferences from variations in ambient background light. Commonly such effects are corrected by the application of lightboxes to isolate the smartphone and sample. However, in this present approach we show the possibility of producing analytically useful and acceptable results using a simple mathematical correction of the RGB data. Using such an approach a linear response was obtained over the range of 3.0 mg/L to 25 mg/L (R² = 0.986) with a limit of detection calculated to be 2.50 mg/L, 2.94 mg/L and 2.61 mg/L for the %R, %G and %B, respectively (3δ). A coefficient of variation of 0.83% was obtained for an 8.0 mg/L hydrogen peroxide standard solution. Using the %G values a mean percentage recovery of 98.5%, with a %CV of 4.3% (n = 5) was obtained for a commercial contact lens cleaning agent solution. This data indicates that the method holds promise for the determination of hydrogen peroxide in such samples.