Geothermal energy, a renewable source of energy, is currently underutilized as geothermal technologies are still under research and development. Enhanced geothermal system (EGS) operation involves passing a fluid through fractured reservoir to exchange heat, followed by energy production on the surface. Despite its potential, limitations of EGS have prevented its widespread utilization. There is a knowledge gap in understanding the triggered thermal, hydrological, mechanical, and chemical processes (THMC) within geothermal reservoir and their effects on the fracture aperture and permeability of the host rock. This paper focuses on investigating how the temperature of injected fluid affects the fracture aperture and permeability of the host rock. To this end, laboratory experiments were conducted to simulate conditions close to an EGS. A granite rock specimen with a longitudinal fracture was subjected to flow-through experiments using a high pressure-temperature apparatus, and the time evolution of fracture aperture and permeability was monitored. The results indicated that fracture aperture and permeability loss are affected by the temperature of injected fluid, particularly at elevated temperatures. Further, the results demonstrated that under constant effective stress, an increase in the temperature of injected fluid and rock would enhance the fracture aperture and permeability loss.