An extracorporeal blood treatment apparatus (1), comprising: an extracorporeal blood circuit (100) having a treatment unit (2), a blood collection line (6) connected to a blood inlet of the treatment unit (2), and a blood return line (7) connected to a blood outlet of the treatment unit (2)； a blood pump (11) configured to control blood flow (QBLOOD) flowing through at least one of said blood collection line (6) and blood return line (7)； at least one infusion line (15, 21, 25) connected to the extracorporeal blood circuit (100), in which the at least one infusion line (25) is connected to the extracorporeal blood circuit (100) at a junction point that it is placed downstream of a blood warming zone (H)； a control unit (10) configured to execute the following procedure: - receiving a first representative value of a desired blood temperature (Tdes) at one end (70) of the blood return line (7) configured to connect to a venous vascular access of a patient (P)； - receiving at least a first signal related to at least one flow rate (QPBP, QREP1, QREP2) of an infusion fluid in said at least one infusion line (15, 21, 25)； - calculate a setpoint value of an operating parameter (TOUT； Pw) that must be imposed on a heating device (200) configured to heat the blood heating zone (H) of the extracorporeal blood circuit (100) with the in order to maintain said desired blood temperature (Tdes) at said end (70) of the blood return line (7)； - in which the set point is calculated based on the input parameters comprising: - at least the first representative value of the desired blood temperature (Tdes) and - at least one selected from the group of: the first signal ( QREP1, QPBP, QREP2) and a second value representative of a temperature (TREP1, TPBP, TREP2) of said at least one infusion fluid in said at least one infusion line (15, 21, 25).Un aparato de tratamiento sanguíneo extracorpóreo (1), que comprende: un circuito sanguíneo extracorpóreo (100) que tiene una unidad de tratamien
