Nickel hydroxide thin film was deposited anodically from an aqueous solution consisting of 10 mM of NiCl2 and 30 mM of (NH4)(2)SO4 at pH 8.5 and heat-treated at different temperatures. The effects of heat-treatment on the electrochromic properties, colour/bleach durability cycle, response time and coloration efficiency, were investigated in a 0.1 M NaOH solution. A significant increase in the number of colour/bleach cycles from 100 cycles (for as-deposited films) to more than 5000 cycles (for films heat-treated at 400 degrees C) was observed, while the absorbance decreased slightly at high temperatures. The change in electrochromic behaviour at different temperatures is discussed based on the electrochromic and thermal analysis.