Junction potenuals for KCl(4M)IIX where X IS one of N&l, L&l, NaOH, HCl, L@04, Ms(NO,h, L&l, ran8mg m concentration from 0 001 to 4 M have been calculated at 0,25, 100°C by usmg the emulation and numerical methods of Parts I and II [J. Bagg, Ekctrochim Acta 3!!, 361, 367 (1990)] Junction pot@& ranged from -362mV(4MHCl.O"C)to26lmV(NaOH4M,2S"C)and their average temperature coefEuents ranged from -0 16 (0 001 M Nail) to 0.05 (4 M LCl) mV C-' The vanation of Juntion potent& with temperature can lead to large hqmd Juntion errors in those pIon determmations where standarbhon and measurement are carned out at markedly merent temperatures For example, the pH of hot water may have to be de&mmed when momtonng cooling systems m the electrical 8enaafion Industry In such a determmahon if a glass electrode stand-m an NBS btier (Na$Oz/NaHCO,) at 25°C was used to measure pH of water at 100°C then thu pH would be sublect to a hqmd Jun&on error of ApH = 0 38 If the water was cooled to 25°C before pH measurement then the Juntion error would be ApH = 0 14 &y word9 won potential, temperature effect, pIon measurement