A new temperature control method for a metallic filament used at high temperature values is proposed by the authors in this paper. The filament used is heated by a switch mode power supply built around a step-down converter. The method uses a microcontroller that implements the temperature control algorithm and also the power supply control loops. The temperature is controlled using a proposed new algorithm based on the output current and output voltage measurements of the power supply already available for implementing the average current mode control. In this way the resistance of the filament can be determined and controlled in a resistance feedback loop. The proposed algorithm will control the resistor value corresponding to the required temperature. The reference resistance value is computed based on the temperature-resistance characteristic of the filament each time a new temperature is introduced in dedicated computer software on a PC. The value is transmitted to the microcontroller via USB interface. The temperature control algorithm and experimentally results are presented in detail in the paper.