The reduction of nitric oxides (NOx) in aircraft engines, gas turbines, or internal combustion engines is a main issue in the design of novel combustion systems. The reduction of the NOx emissions might be reached by lean combustion. However, the major issue is the stabilization of the flame under lean conditions. In this context, the present work investigates the possibility of increasing the combustion efficiency of a lean flame through the employment of a plasma actuator, operated by both nanosecond repetitively pulsed high voltage (NRPP) and sinusoidal DBD high voltage (HV). Different actuation conditions have been tested to stabilize and improve the efficiency of a lean non premixed methane/air flame in a Bunsen-type coaxial burner with central fuel jet. An image processing approach was used to characterize the flame behavior near blowout conditions