Surface enhanced Raman scattering (SERS) of halate ions in silver colloids is studied by near infrared (NIR) laser excitation.Ions of ClO－3 and BrO－3 in silver colloids give rise to SERS bands at about 226 and 158cm－1,respectively while IO－3 ions on colloidal silver surface result in two Raman bands at about 750 and 334cm－1.These results indicate that the interactions of ClO－3 and BrO－3 ions with silver surface are through their lone pair electrons of Cl and Br.Nevertherless,IO－3 ions bond to silver surface through their negatively charged O－.The interaction strength of halate ions with silver are measured to be BrO－3>ClO－3≈IO－3.The enhancements of the Raman modes of pyridine caused by addition of halate ions increase in the order ClO－3－3－3.The enhancement mechanisms in NIR SERS are discussed.