This work is focused on electroless coating of Ni-B nanolayer on B4C particle surfaces. The B4C particles used are approximately 2 mu m in average size. Effects of activation agent PdCl2, complexing agent C2H8N2, and reducing agent NaBH4 addition rate are studied. The solids loading of B4C is 0.625 g/L and the concentration of Ni2+ ions is 0.004 mol/L in the electroless coating solution. Scanning electron microscopy (SEM) shows that when B4C:Pd2+ molar ratio is 1:0.005, a Ni-B nanolayer with the smallest Ni-B nodule size covers the B4C particle surfaces. Complexing agent C2H8N2 decreases Ni2+ ion release rate. Ni:C2H8N2 ratio of 1:6 is the preferred complexing agent amount for achieving a continuous Ni-B nanolayer. The Ni-B nanolayer formation is also strongly dependent on the rate that Ni2+ ions are reduced. Slow Ni2+ reduction leads to increased Ni content in the Ni-B nanolayer. When the above three factors are combined at the optimal values for the electroless coating process, well-defined Ni-B nanolayer is obtained. SEM cross section analysis shows the Ni-B nanolayer completely covers the B4C particles with less than 55 nm thickness.