The thermal properties of freely suspended GaAs nanowires are investigated by applying a method which relies on laser heating and the determination of the local temperature by Raman spectroscopy. In order to determine the values for the thermal conductivity kappa, the fraction of the laser power absorbed inside the GaAs nanowire is estimated by numerical simulations. The thermal conductivity of nanowires with homogeneous diameter is found to lie in the range of 8-36 W m(-1) K-1. The change of the temperature profile in the presence of a tapering was investigated. Furthermore, we discuss the influence of laser heating in ambient conditions on the value of kappa. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3532848]