Optimal cooling strategies for the secondary cooling zone of the continuous casting process are crucial for the production of high-quality steel slabs. To find such strategies it is necessary to understand the influence of spray properties on the cooling performance. Our experimental set-up allows a comparative monitoring of water droplet impingement characteristics on cold and hot steel surfaces. Droplet sizes and velocities at different air-mist spray conditions were examined by laser diffraction analysis and high-speed imaging. Partly, discrimination between incoming primary spray and secondary droplets formed during splashing could be achieved. For all experiments, the area of spray overlapping was of special interest.