A scanning laser electrochemical microscope was used to study spatial variations in the photocurrent generated at a n-type GaAs surface under conditions of photodissolution. In order to pin insight into the origin of photocurrent image contrast the influence of parameters such as electrode potential, series resistance and laser spot velocity were investigated in a systematic manner. Experimental photocurrent distance profiles were compared to theoretical predictions taking into account minority carrier generation, surface recombination and electron transfer processes. The results agree well with quantitative information obtained from localised intensity modulated photocurrent spectra (IMPS). The photocurrent contrast at hotspots is found to be due to local variations in the maximum photocurrent response in the absence of recombination process,