A surface mountable thermistor comprises a resistive device, first and second electrodes, and at least one heat conductive dielectric layer. The resistive device contains first and second electrically conductive members and a polymeric material layer laminated therebetween. The polymeric material layer exhibits PTC or NTC behavior. The polymeric material layer and the first and second electrically conductive members commonly extend in a first direction. The first electrode is electrically coupled to the first electrically conductive member. The second electrode is electrically coupled to the second electrically conductive member and is insulated from the first electrode. The heat conductivity of the first electrode or the second electrode is at least 50 W/mK. The heat conductive dielectric layer comprises polymeric insulation matrix and heat conductive filler, and is disposed between the first electrode and the second electrode. The heat conductivity of heat conductive dielectric layer is between 1.2 W/mK-13 W/mK.