Laser sintering of metal nanoparticles is a key technology for high-performance printed electronics fabricated on heat-sensitive substrates such as glass or plastic. Although laser-sintered electronic devices have been successfully fabricated, the role of the induced temperature field in the laser sintering process has not been reported thus far. In this work, the effect of temperature on the laser sintering process is described for the first time using a two-dimensional transient heat conduction equation for inkjet-printed silver nanoparticle ink. The in situ electrical resistance was measured to estimate the transient thermal conductivity and hence the temperature of the sintered ink during the laser sintering process. To verify the estimated laser sintering temperature, the morphology of furnace-sintered silver nanoparticle ink was compared with that of laser-sintered ink. The electrical characteristics and surface morphology of laser-sintered ink are found to be related to the process temperature.