Our aim is to get basic data to increase the efficiency of micro horizontal axis wind turbine (HAWT) systems. The experiments were carried out in an open type wind tunnel. We measured the turbine performance of five-bladed wind turbines with MEL002 and MEL081 airfoil cross-sections. Flow characteristics of rotating blades of the turbine were observed using the oil-film visualization technique. Flow visualization allowed the identification of laminar flow, laminar separation bubble formation, flow reattachment, turbulent boundary layer, and turbulent separation. The complex patterns on the rotating blade surface were confirmed and identified by the oil-film visualization method. The performance of the wind turbine with MEL081 airfoil section was better than the other airfoil sections at low wind speed.