Used in plastic and cable industries, Apparatus for Temperature of Deflection under Load consists of a specimen support, an immersion bath, a set of weights under deflection –measuring device. The specimen support consists of a two parallel metal supports having rounded edges fixed at a specified distance on an aluminium frame. Load is applied on the test specimen midway between two supports. This block is fitted to the lower end of the vertical rod, which is guided inside a metallic sleeve and is constrained to move without rotating along a vertical axis. The upper end of the vertical rod carries a load carrying plate on which loading weight can be placed to load the test specimen. All the parts are made of aluminium having same co-efficient of linear expansion. The immersion bath consists of a double walled reservoir having the inner walls made from Stainless Steel sheet and outer walls made of mils steel sheet. The space in between the walls is filled with glass wool insulation. The liquid in the bath is heated by means of an immersion heater and the rate of rise of temperature controlled with the help of an electronic voltage regulator. A digital temperature controller is provided to restrict the maximum temperature of the bath. The deflection of the specimen is measured with the help of dial gauge.