In this study, we propose a simple autotuning method using proportional controller. A second order plus time delay model is used in the on-line closed-loop identification and tuning of PID controllers. This model can approximate processes over a wider frequency region than a first order plus time delay model, which is often employed in model-based autotuning methods. Moreover, since the identification method requires only a simple least squares method to estimate the model parameters, no complex numerical techniques such as root-finding or optimization methods are employed, thus making it practical, unlike many other previous identification methods. Simulation studies demonstrate that the proposed method shows satisfactory identification and better control performances than other previous methods for various processes. In the identification step, it shows insensitivity to measurement noise and input disturbances. The results of the experimental study confirm its validity and capability and show its promise in industrial situations.