The surface ablation cell (SAC), a laboratory equipment for determining surface concentration profiles, has been utilised to characterise surface ion exchange processes in float glass. In this paper, single-side ion exchange is reported. Data on the ion concentration profiles were used to calculate diffusion coefficients as well as the activation energy for K +-Na+ ion exchange. The air-sides of float glass samples were treated with two different salt mixtures, (I) 2:1 KNO3:KCI, and (II) 1:2 KNO3:KCl, (both by weight), and heated to different temperatures below Tg, 460-520°C. The diffusion coefficients calculated using a Green's function approach were in the ranges (I) 1.4×10-11 to 6.8×10-11 and (II) 1.8×10-11 to 6.0×10-11 cm2/s while those calculated using Boltzmann-Matano were in the ranges (I) 5.7×10 -11 to 14×10-12 and (II) 3.4×10-12 to 6.0×10-12 cm2/s. Average values of the activation energies obtained through the Green's function were (I) 111.0 kJ/mol and (II) 99.8 kJ/mol for the different salt mixtures.