The properties and ability to diagnose the presence of NH3 of PVA-butterfly pea films was investigated. The response of the PVA-butterfly pea extract films to NH3 in terms of their color change will be measured using a colorimeter (Hunter Lab, CIEAB) and calculated the total color difference according to ASTM D2244-09b. The NH3 solution will be prepared at four different concentrations (0.01, 0.05, 0.1 and 1.0 M). The PVA-BP extract film will be placed at 1 cm above the NH3 solution in a closed container (5 cm x 5 cm x1cm) for 2 hours or until liquid – vapor equilibrium is reached at 4 ˚C and room temperature. After that, the PVA-butterfly pea extract film will be taken out to measure the change in color immediately.