Solid oxide fuel cell/gas turbine (SOFC/GT) hybrid systems harness the capability to operate nearly 15 to 20 percentage points more efficiently than standard natural gas or pulverized coal power plants. Though the performance of these systems is quite promising, a number of system integration challenges, primarily with regards to thermal transport, still remain. It is for that reason that the Hybrid Performance Project (HyPer) facility, a Hardware-in-the-Loop SOFC/GT hybrid simulator, was built at the National Energy Technology Laboratory in Morgantown, WV. The HyPer facility couples an actual gas turbine with a combination of hardware and software that are used to simulate an actual SOFC. The facility is used to empirically address the system integration issues associated with fuel cell/gas turbine hybrids. Through this dissertation project, the software component of the SOFC simulator was upgraded from a 0-D lumped SOFC model to a 1-D, distributed, real-time operating SOFC model capable of spatio-temporal characterization of a fuel cell operating with a gas turbine in a hybrid arrangement. Once completed and verified, the upgraded HyPer facility was used to characterize the impact of cold air by-pass and initial fuel cell load on electrochemical start-up in an SOFC/GT hybrid environment. The impact of start-up on fuel cell inlet process parameters, SOFC performance and SOFC distributed behavior are presented and analyzed in comparative manner. This study represents the first time that an empirical parametric study, characterizing system operation during electrochemical start-up has been conducted.