The conductive heat flux can be modeled by a vector: in a real anisotropic material, the contribution of each directional components is not easy to measure. The transient plane source technique, also known as Hot-Disk, stands as a valid device for the measurement of thermal diffusivity in this kind of materials if some geometric requirements are metfor the reparation of the samples. In this paper, the theoretical derivation of the equation ruling the computation of the thermal diffusivity and conductivity in anisotropic material using the Hot-Disk device is presented and used for obtaining these properties for three tree species from the Northeast of Italy: oak, spruce and larch