The microstructures of electroless Ni-P and Ni-Cu-P deposits were investigated in the presence of thiourea and saccharin with AFM. The phosphorus contents and crystallinity of the deposits were investigated. Saccharin was found to refine the nodular structure of the Ni-Cu-P deposit, while not affecting the P% of the Ni-P and Ni-Cu-P deposits. On the other hand, thiourea was found to affect the P% and surface roughness of the Ni-P deposit. Thiourea does not exhibit nodular refining effect on the deposit.