Abstract: Method and apparatus for self-tuning a Proportional Integral-Derivative controller for controlling at least one load characteristic to a predetermined setpoint from calculated values of Proportional Band (PB), Integral Time Constant (ITC) and Derivative Time Constant (DTC) by application of power to the load, establishing a cut-off point to remove power to the load, determining the slope of a measured value of the at least one load characteristic and starting an integral time counter upon detection of the power cut-off point, determining at least one value X.sub.min at which the value of the measured value decreases by a fixed percentage, determining the maximum value X.sub.max of the at least one load characteristic, calculating the values of the PB, ITC and DTC by determining the rise X.sub.r =X.sub.max -X.sub.min and determining PB and ITC from a stored table relating X.sub.