In this paper, power system state estimator (SE) solution using extended state estimation matrix measurements (SEMM) is presented. Within an optimum measurement placement environment, the extended SEMM is formed to enhance the state estimator solution in accuracy. The main idea is to maintain the readings from available measurement units to extend the new SEMM. This is determined by using the correlation and/or regression analysis of the new measurements and the available measurements. Absolute voltage error is used to analyze the system performance for IEEE 14-bus and IEEE 30bus testing systems where the estimation errors are compared for both the conventional method and extended SEFM method.Index Terms-accuracy, coefficient of determinations, extended SEMM, extended measurements, optimal environment, power systems, state estimation.