The use of advanced high strength steels (AHSS) in the body-in-white of automobiles has simultaneously led to reduced weight of vehicles and increased passenger safety. In continuous galvannealing lines, the steel strip is reheated 50 - 80 °C following the zinc bath to enable diffusion of iron into the zinc layer. Due to a change in transformation kinetics and therefore in transformation products, the mechanical properties of the material can be influenced by this reheating step. The influence of the galvannealing process on the microstructure and mechanical properties of two conventional dual-phase steels, two high-ductility dual phase steels and one trip steel was examined. All samples for the simulated heat treatments were taken from steel strips cold-rolled on industrial scale. To characterise the transformation behaviour of the five materials, continuous and isothermal dilatometric measurements were carried out. In addition, the heat treatment cycle of a continuous galvannealing line was simulated on laboratory scale, including interrupted and complete cooling cycles. The resulting microstructures were examined by light-optical microscopy, scanning electron microscopy and magnetic measurements of the content of retained austenite. Hardness measurements and tensile tests were used to characterise the mechanical properties of the materials after the heat treatment cycles described above.