Abstract <p>High-speed imaging is used to investigate droplet impact dynamics on cylindrical surfaces, focusing on the effects of the impact height <i>H</i>, the initial diameter <i>D</i>₀, and the wall roughness <i>Ra</i> on circumferential spreading. The results show the following: as <i>H</i> increases from 19 to 79 mm, the maximum circumferential spreading length increases by 39.02% on the inner surface and by 57.88% on the outer surface, the outer surface consistently exhibiting larger spreading due to convex geometry promoting circumferential flow. An increase in <i>D</i>₀ from 2.11 to 3.34 mm enhances the maximum spreading length by 82.94% on the inner surface, while the spreading factor increases by 21.05% only, revealing a nonlinear dependence of the spreading factor on the droplet diameter. In contrast, wall roughness has a negligible effect within the tested range, suggesting inertia-dominated spreading. At higher impact conditions, finger-like splashing occurs, with a lower critical Weber number on the outer surface, attributed to enhanced air entrainment over convex geometries. In addition, droplet coalescence leads to prolonged oscillation and delayed stabilization on the outer surface, highlighting the role of curvature in energy dissipation. Correlations between the maximum spreading factor and the Weber number are established for predictive purposes. These findings provide insight into the droplet behavior on curved surfaces relevant to spray cooling and anti-icing applications.</p>