Metal nanoparticles are of great interest for diverse applications due to their unique properties; however, for sensing and other targeted applications, it is necessary to design the surface chemistry to enable their desired function. We have synthesized citrate-stabilized, spherical gold nanoparticles 3-5 nm in diameter and subsequently exchanged the surface-capping citrate with a model alkanethiol in a stirred, biphasic water/hexane medium. The change in surface chemistry switches the particle solubility preference from the aqueous to the organic environment. We have instigated the nanoparticle phase transfer with time resolved UV-Visible absorbance spectroscopy of the aqueous phase, monitoring a diminishing central peak around 500 nm throughout the phase transfer. The absorbance peak indicates a consistent size distribution of stable nanoparticles within the aqueous layer throughout the transfer. TEM images of the organic phase were taken at strategic intervals up t = 20 hours. Nanospheres from the aqueous phase were analyzed with TEM for time t = 0 minutes and t = 20 hours. The particle distributions were essentially the same for the organic layer over time, suggesting that particle size—and consequently surface energy—was not a dominant factor in the kinetic mechanism for the phase transfer.