The use of miniaturised isotachophoresis, performed on a planar poly(methyl methacrylate) device with integrated platinum conductivity electrodes, for the analysis of the ascorbate content of photographic developer solutions has been investigated. An electrolyte system has been developed which enabled the analysis to be made without interference from any of the other components in the developer solution, a number of which were present at significantly higher concentrations than that of the ascorbate ions. Using this system, the ascorbate content of the developer solutions could be analysed in under 6 min. The limit of detection for ascorbate using miniaturised isotachophoresis was calculated to be 0.011 mmol dm−3.