The mixed effects of heat and charge transports have been studied at room temperature for NiCu and CoCu multilayers with currents perpendicular to the interfaces as well as Ni and Co homogeneous nanowires. In order to carry out this analysis, magnetothermogalvanic voltage (MTGV) measurements have been performed. The method consists in monitoring an alternating voltage response that arises when an oscillation of the temperature of the nanostructure is applied and a steady current crosses the nanostructure. Different responses were observed for thicknesses of the ferromagnetic layer larger or shorter than the spin diffusion length. Qualitatively different MTGV profiles were also observed for Ni and Co homogeneous nanowires. These results demonstrate the importance of spin relaxation processes produced in ferromagnetic/nonferromagnetic (FM/NF) interfaces as well as in FM layers for the MTGV response. © 2006 American Institute of Physics.