An apparatus for the continuous automatic measure of the filterability threshold temperature of a liquid substance comprising a block made of a metal having a high thermal inertia, said block having an external surface and a closed recess therein, a cooling liquid substantially filling said recess, said cooling liquid having a freezing temperature substantially lower than the average filterability threshold temperature of the type of liquid to be analyzed, cooling means on said external surface of said block adapted to cool said block, an electrically conductive metal capillary tube immersed in said cooling liquid and having an inlet end and an outlet end emerging from said block, said tube being electrically insulated from said block, pump means for delivering the liquid to be analyzed to said tube at a constant volume flow rate, electrical connecting means to connect both ends of said tube with the terminals of an electric power supply respectively, switch means interposed on one of said electrical connecting means, pressure responsive meeans in connection with said switch means whereby said electric power is supplied to said electrically conductive metal capillary tube when the difference between the inlet pressure and outlet pressure of said capillary tube exceeds a first predetermined value and suspends said supply of electric power when said pressure difference reaches a second predetermined value lower than said first value, thermosensitive means adapted to measure the temperature of the liquid to be analyzed in the outlet end of said capillary tube and means for recording the temperature measured by said thermosensitive means.