Temperature dependent optical properties of RF-sputtered c-axis oriented ZnO:N thin film have been investigated. Surface Plasmon modes are excited at the metal-dielectric interface in the Kretschmann-Reather configuration using prism coupling technique. Effect of ZnO:N thin film deposited over Prism-Au structure on the SPR reflectance is studied over a wide range of temperature from 300–500 K at 633 nm wavelength. The value of dielectric constant of ZnO:N film obtained by fitting the experimentally obtained data with the theoretically generated SPR curve at the optical frequency is found to increase linearly with temperature. The increase in dielectric constant (4.03 to 4.11) with increase in temperature from 300 K to 500 K indicates a promising application of the system as an efficient low-cost temperature sensor.