Co mputational electro magnetics (CEM) is applied to model the interaction of electro magnetic fields with the objects like antenna, waveguides, aircraft and their environment using Maxwell equations. In this paper the strength and weakness of various computational electromagnetic techniques are deliberated in detail. Performance of various techniques in terms accuracy, memory and co mputation time for application specific tasks such as modeling RCS (Radar Cross Section), space Applications, thin wires and antenna arrays are presented in this paper. Co mmercial software codes has certain limitations, Agilent ADS could not model 3D structures, HFSS is accurate but execution time is h igh, WIPL-D ® does not support modeling Inhomogeneous dielectrics embedded metal objects and periodic structures. IE3D ® is not suited for geometry with fin ite details. However for regular shapes like rectangular patch MOM based IE3D provides accurate results than FEM based IE3D. The co mp licated structures are dealt with accuracy by using CST Microwave Studio ® and HFSS ® . Although CST and HFSS has similar interface in dealing with geo metry with fine details, CST had edge over HFSS software as it starts in time do main and ends in frequency domain. HFSS uses Finite Element Method (FEM ) to arrive at frequency domain solution. FEKO ® has two main solvers MOM based and GTD based. GTD based FEKO is good in handling large structures like reflector antennas.