The deposition experiments were carried out under high pressure (7 MPa) at 285 °C using model compounds (α-hematite) to investigate the deposition process of crud on boiling surfaces. The effects of several factors, such as the diameter of the model particles (0.15 to 2.3 µm), pH (7 to 13), and heat flux of the heated surfaces (5 to 16 W/cm2), on the deposition rate during the initial stage were investigated. It was found that the deposition rate of the hematite particle, having a narrow particle size distribution, strongly depends on the particle diameter and pH of the crud suspension. An explanation of these results was based on the assumption that the electrokinetic interaction between the particle and the surface plays an important role in the deposition process of the crud particles. Furthermore, it was found that the deposition rate of the hematite, having a narrow particle size distribution, deviates from the linear proportionality.