Saturated pool boiling heat transfer has gained a great interest for high-heat-flux thermal management due to its quite simple system. However, the critical heat flux (CHF) is much smaller than the heat flux in the power device. For improving CHF, the present study proposes a hydrophilized free particle bed placed on a heating surface. The diameter of the free particle D is 1.0, 2.0, or 3.0 mm, and the number of the particle layer N is 1, 2, or 3. The boiling curves of the saturated pool boiling are obtained with distilled water under atmospheric pressure. The results shows that the CHF varies with D and N. When D is 1.0, 2.0 or 3.0 mm, N that maximizes the CHF is 2, 2, and 1, respectively. The visualization results indicate that there are two effects of the free particle bed on CHF: 1) inhibition of a bubble coalescence, and 2) liquid supply by a particle penetration into vapor. Since the particle weight varies with D, there is an optimal N for each particle. As the result, the highest CHF is 227 W/cm² in the case of D is 1.0 mm and N is 2, which is 2.1 times larger than that on a smooth surface without the free particle bed. This value is also 1.1 times larger than that with non-hydrophilized particles. This indicates that the hydrophilized particles are more likely to penetrate the vapor, and a continuous liquid supply can be realized. Moreover, the incipient boiling wall superheat is decreased by the free particle because corner cavities are formed with the heat transfer surface. Therefore, the hydrophilized free particle bed is effective for enhancement of both the nucleate boiling performance and CHF.