The present study experimentally investigates the outcome of Urea-water solution (UWS) spray impingement on a heated surface which is relevant to a NO_x reduction strategy in diesel engines based on the Selective catalytic reduction (SCR) technology. High-speed pulse-shadowgraph technique was employed to capture the unsteady spray-wall impingement process, while the time-varying droplet size and velocity was measured using the Interferometric Laser Induced Droplet Sizing (ILIDS) technique. Based on the spray visualisation and droplet sizing measurements, a regime map is proposed by using suitable non-dimensional parameters for a wide range of surface temperature of the wall.