The aim of the paper is to present the synthesis method of classic PID controller for a class of unstable plant. The proposed method based directly on Skogestad paper, where analitical synthesis of PID controllers in described.- The aim of　the paper is to present the synthesis method of classic PID controller for a class of unstable plant. The proposed　method based directly on Skogestad paper, where analitical synthesis of PID controllers in described.