In the micro-forming process when the thickness of the sheet material is comparable to the intrinsic length scales of that material, deformation behaviour differs from that which is expected in the macroscopic sheet material. In this study, size effects of SS304 foils have been investigated using tensile and limiting dome height tests along with careful microstructural investigations. SS304 foils of differing thicknesses but similar grain size have been deformed under varying strain path conditions to capture the impact of foil thickness on the mechanical response and microstructure evolution. Formability curves for SS304 foils constructed from limiting dome height tests show that limit strains increase with increasing foil thickness. Microstructure investigations highlight the importance of grain misorientation, twin fraction and texture on the formability of SS304 foils. © IMechE 2018.