Extended X-ray absorption fine structure (EXAFS) spectroscopy and transmission electron microscopy (TEM) have been used to investigate Ni/Co bimetallic nanoparticles (bi-MNPs) in carbon species such as single-walled carbon nanotubes (SWNTs) produced via laser vaporization of a carbon-metal mixture. Results from selected area diffraction (SAD) and dark field TEM imaging measurements indicate that the structures of these nanoparticles are face-center-cubic. and energy-dispersive X-ray (EDX) elemental analysis shows that each of the nanoparticles examined contains 50 +/- 5% of Ni and Co. The average coordination numbers of the nearest neighbors for Ni and Co in the bi-MNPs derived from the EXAFS data are 10.0 and 11.0, respectively. The squares of disorders (sigma(2)) for the Co and Ni in those nanoparticles are 0.0053 and 0.0054, The former is slightly lower than that of the Co bulk, 0.0059, whereas the latter is identical to the value for the Ni bulk. Using these coordination numbers and assuming that all the nanoparticles are in the bimetallic form, their average size is estimated to be 3 nm, much smaller than the 8-nm average size obtained from the TEM measurements, A detailed analysis of the EXAFS data using Fourier filtering and single scattering theory has revealed that the surface of the nanoparticles is predominantly occupied by Ni atoms.