The dynamic response of continuous processes is a key issue for their control. To represent this
response, first order models are used, mainly because of their simplicity and the lack of simple methods for parameter estimation of higher order models. Although first order models may be sufficient in many cases, there are times when a higher order model needs to be used to achieve good control. This paper presents a simple graphical procedure for the estimation of the two time constants, the gain, and the dead time of a second order linear model. The procedure uses only four readings from the step response curve of the processes, and very simple formulas to determine parameter values.