The gradual increase in the amount of fines (<20 mu m) deposited in a hydrotreating reactor results in a sudden pressure drop, leading to premature reactor shutdown. In addition to the nature of the fine particles, it is believed that the particle deposition is a function of the process parameters of the reactor. Among the process conditions that influence the hydrotreating process, temperature and pressure have been identified as key variables; therefore their impact on fines deposition on NiMo/gamma Al2O3 catalyst was studied. Model fine particles were suspended in light gas oil (LGO) feed, and the feed was hydrotreated in a batch reactor. The catalyst was characterized to understand its interaction with the model fine particles. Mass balance results and SEM images were used to quantitatively analyze the deposition of fine particles on the catalyst bed. The statistical analyses were performed using central composite design (CCD) to optimize the hydrotreating conditions for bed deposition and sulfur conversion as a function of process parameters such as temperature (355-375 degrees C), pressure (1200-1400 psig), and particle loading (1-1.5 g of fines) in 200 mL of oil. High fines concentration in the feed (particle loading) and high temperature led to higher bed deposition. The results obtained helped an understanding the impact of process parameters on particle deposition in a batch reactor and not in a packed bed reactor. The optimum temperature to have a significant sulfur conversion with least fines deposition for LGO feed with process conditions within the boundary of this research for a batch reactor was found to be in range of 360 to 364 degrees C.