In the present work the temperature profile variations generated in rectangular specimens built using the Fused Deposition Modeling (FDM) process, at different printing speeds and orientations, were investigated. The temperature recordings were achieved by the integration of temperature sensors throughout the 1st and/or 21st building layer of the specimens. The experimental results show that the temperature values inside the specimen re-main above the glass transition temperature (Tg) even at the end of the fabrication process. Higher values were obtained when increasing the printing speed and decreasing the printing path. The experimental results were compared to the corresponding ones derived by simulation of the thermal diffusion problem via Finite Element Analysis. The calculated maximum temperature values were in good agreement with the experimentally recorded ones.