Welding together dissimilar materials, and, in particular, aluminium alloys to steel, has always been a challenge because of the significant difference in their mechanical, thermo-physical and metallurgical properties which causes the formations of hard and brittle intermetallic phases in the welding zone [1]. Recently, EWM® had developed a welding process known as ColdArc®, where the heat input and arc stability are precisely controlled [2]. The present study was designed to investigate the static and fatigue behaviour of aluminium-to-steel thin welded joints manufactured using EWM ColdArc® welding technology. Butt, cruciform and lap hybrid welded joints (Fig.1a-c) were fabricated to study, in terms of nominal stress approach, their tensile strength as well as their fatigue behaviour