Metal-semiconductor hybrid structures are important in a number of technologies such as sensors, catalysis, integrated circuits and more broadly in nano-and microsystem technologies. Electroless deposition, in this case, galvanic displacement process, is a simple way to develop such metal-semiconductor hybrid systems. In this review, we will first briefly discuss on the electroless deposition of gold nanoparticles and then look into the details of galvanic displacement of gold on silicon. From the fundamental aspects of galvanic displacement of gold on silicon, we will see how the experimental parameters such as deposition time, silicon surface, influence of light/laser during deposition, etc. affect the gold morphology on silicon. We will then explore the potential applications of such hybrid structures, especially its sensoric and catalytic properties.