In the current study, a network-based resistor model has been developed for thermal analysis of a complex opto-electronic package called small form-factor pluggable device (SFP). This is done using the DEvelopment of Libraries of PHysical models for an Integrated design (DELPHI) methodology. The SFP is an optical transceiver widely used in telecommunication equipments such as switches and routers. The package has a detailed construction and typically has four fixed heat generating sources. The detailed model for the SFP is constructed and calibrated using a natural convection experiment. The calibrated detailed model is used for generating the limited boundary-condition-independent compact thermal model (CTM). Limited boundary-condition-independence, in this case, refers only to a small subset of all “thinkable” boundary conditions that are experienced by the SFP device in practical situations. The commercial optimization tool developed by the DELPHI team, DOTCOMP , is used for generating the compact thermal model. A detailed validation of the CTM of the SFP in real-time applications using FLOTHERM 7.2, a computational fluid dynamics-based thermal analysis software package, is performed. The results show excellent agreement between the results predicted by the SFP CTM with the data from the detailed model. The SFP CTM predicts the junction temperature of the four power-dissipating components and the heat flows through the sides with relative error less than 10%.