The linear cofactor difference extrema of metaloxide-semiconductor field effect transistor (MOSFET) drain current are presented in this paper and their application to extract MOSFET parameters is demonstrated. The extrema of the characteristic drain current are obtained by the applying the linear cofactor difference operator to the drain current versus gate voltage curve in the linear region. These extrema can be directly used to find the threshold voltage and mobility of a MOSFET. The method has been tested with experimentally fabricated MOSFETs and simulation data obtained by the device simulator DESSIS-ISE. The results agree well with those obtained with the standard second-derivative method, which demonstrates the validity of the method presented.