At the Division of Electricity at Uppsala University there is an experimental rig for hydroelectric generators. The experimental rig’s vital part is a 12-pole synchronous machine, whose electrical characterizing parameters (resistances, inductances and time constants) are unknown. The aim of this thesis is to characterize the machine in its current state by perform a Standstill Frequency Response (SSFR) test. From the analysis of the measurement data, which is a part of the test, a set of basic parameters have been received. Based on this set of basic parameters a mathematical model has been matched to fit the measurement data so that the last unknown parameters could be obtained. The result of the analysis and fit gave a set of parameters. The set of parameters resulted in a more or less good fit to the measurement data. It has been shown that even though the parameters are based on the generator itself it does not necessarily give the best fit. As a verification of the parameters, which has been received from the test, further work is needed by implementing the parameters into a dynamic model and then compare that model with measured responses from electrical or mechanical interference of the generator.