Fluid warming device for an extracorporeal blood treatment apparatus, comprising: a casing delimiting a heating zone accommodating or configured to accommodate a fluid warming path, wherein the fluid warming path has an inlet and an outlet connected or connectable to an extracorporeal blood treatment apparatus; heating elements operatively active in the heating zone to heat the fluid warming path; at least an outlet temperature sensor operatively active at the outlet of the fluid warming path to convey a measured outlet temperature (To) of a fluid leaving the fluid warming device; an electronic control unit operatively connected at least to the outlet temperature sensor; wherein the electronic control unit is configured to perform at least the following procedure: - receiving, from the outlet temperature sensor a signal correlated to the measured outlet temperature (To); - correcting the measured outlet temperature (To) through a correction model to obtain an actual fluid outlet temperature (Tout); - adjusting a heating power (Ph) of the heating elements to keep the actual fluid outlet temperature (Tout) at a set reference temperature (Tset); wherein the correction model is a mathematical model of a measurement error, wherein the correction model is an empirical model of the measurement error derived from a plurality of experimental data sets, the measurement error being a difference between the measured outlet temperature (To) and the actual fluid outlet temperature (Tout); characterized in that the correction model is derived from a regression analysis of the measurement error collected through the plurality of experimental data sets versus a plurality of parameters (To, Tplate, Ph, Ti, Tcomp1, Tcomp2, Q, P/(To-Ti), Pw, Ta) collected through said plurality of experimental data sets, wherein said parameters (To, Tplate, P, Ti, Tcomp1, Tcomp2, Q, P/(To-Ti), Pw, Ta) comprise the measured outlet temperature (To) and one further working parameter (Tplate, P, Ti, Tcomp1, Tcomp2, Q, P/(To-Ti), Pw, Ta) of the fluid warming device and/or of the extracorporeal blood treatment apparatus. a casing delimiting a heating zone accommodating or configured to accommodate a fluid warming path, wherein the fluid warming path has an inlet and an outlet connected or connectable to an extracorporeal blood treatment apparatus; heating elements operatively active in the heating zone to heat the fluid warming path; at least an outlet temperature sensor operatively active at the outlet of the fluid warming path to convey a measured outlet temperature (To) of a fluid leaving the fluid warming device; an electronic control unit operatively connected at least to the outlet temperature sensor; wherein the electronic control unit is configured to perform at least the following procedure: - receiving, from the outlet temperature sensor a signal correlated to the measured outlet temperature (To); - correcting the measured outlet temperature (To) through a correction model to obtain an actual fluid outlet temperature (Tout); - adjusting a heating power (Ph) of the heating elements to keep the actual fluid outlet temperature (Tout) at a set reference temperature (Tset); - receiving, from the outlet temperature sensor a signal correlated to the measured outlet temperature (To); - correcting the measured outlet temperature (To) through a correction model to obtain an actual fluid outlet temperature (Tout); - adjusting a heating power (Ph) of the heating elements to keep the actual fluid outlet temperature (Tout) at a set reference temperature (Tset); wherein the correction model is a mathematical model of a measurement error, wherein the correction model is an empirical model of the measurement error derived from a plurality of experimental data sets, the measurement error being a difference between the measured outlet temperature (To) and the actual fluid outlet temperature (Tout); characterized in that the correction model is derived from a regression analysis of the measurement error collected through the plurality of experimental data sets versus a plurality of parameters (To, Tplate, Ph, Ti, Tcomp1, Tcomp2, Q, P/(To-Ti), Pw, Ta) collected through said plurality of experimental data sets, wherein said parameters (To, Tplate, P, Ti, Tcomp1, Tcomp2, Q, P/(To-Ti), Pw, Ta) comprise the measured outlet temperature (To) and one further working parameter (Tplate, P, Ti, Tcomp1, Tcomp2, Q, P/(To-Ti), Pw, Ta) of the fluid warming device and/or of the extracorporeal blood treatment apparatus.