Recent studies have shown that gold nanorods are highly effective agents for conversion of visible and near infrared (NIR) light into heat. Thermal therapy that utilizes this effect is called Plasmonic Photohermal Therapy (PPTT), where light absorption by photothermal agents (plasmon-resonant gold nanorods) caused kinetic energy to increase, resulting in heating of the area surrounding the agent. A primary understanding of optical and thermal properties of gold particles at nonscale level is still unclear. Due to the limitations of current equipment for nanoparticle characterization, numerical methods and computational models are widely used to understand the physic at the nanoscale. In this thesis fininte element analysis and spatial modulation spectroscopy were used to develop and test a computational model to characterize optical properties of a single gold nanorod.