Incremental forming process has become more and more popular because of its ease of forming and capability to produce different part shapes using same machine set-up. This article describes an experimental study on the influence of process parameters in single point incremental forming (SPIF) on the surface roughness and thickness of formed part. Experiments are performed on aluminium alloy (Al-1050) sheet on a 3-axis CNC milling machine. Hemispherical-headed tool of stainless steel (SS-304) is used to study the effect of tool path, tool diameter and pitch on the surface roughness (R a ) and thickness (t) of formed part. Design of experiment (DOE) full factorial plan is used, and results are plotted using ANOVA. Considerable effect of tool diameter is found on the surface quality of formed part. © 2016, © 2016 Taylor & Francis.