Direct electroless nickel plating on n-si(100) wafers in alkaline solutions was demonstrated without any activation procedure in advance,the effect of pH and tem- perature of the solutions on size of metal particles in depos- its was examined,and also the element contents os deposits were analyzed by energy disperse spectroscopy (EDS).The results indicated that the size of metal particles increases with increasing temperature or decreasing pH.The possible mechanism of nickel deposition on n-Si(100) was discussed in terms of semiconductor electrochemistry,and the forma- tion of nickel seed crystal on Si was mainly attributed to the generation of atomic hydrogen by electron capture of water molecule from the semiconductor in alkaline solutions. Direct electroless nickel plating on n-si (100) wafers in alkaline solutions was demonstrated without any activation procedure in advance, the effect of pH and temperture of the solutions on size of metal particles in depos- its was examined, and also the element contents os deposits were analyzed by energy disperse spectroscopy (EDS). The results indicated that the size of metal particles increases with increasing temperature or decreasing pH. The possible mechanism of nickel deposition on n-Si (100) was discussed in terms of semiconductor electrochemistry, and the forma tion of nickel seed crystal on Si was primarily attributed to the generation of atomic hydrogen by electron capture of water molecule from the semiconductor in alkaline solutions.