Interrelations between soil pH and exchangeable sodium percentage (ESP) were examined using soils from the Burdekin River area in tropical Queensland. Highly significant correlations were found but the goodness of fit differed between groups of soil profile classes. In general, Typic Natrustalfs of the flood plains had better relationships (r2= 0.85) between these soil properties than did the Chromusterts (r2= 0.50). The regression ESP = 1.935 × 10‐5pH6.205 (r2 = 0.61; n= 288) for all soils and depths underestimated ESP in Typic Natrustalfs groupings and overestimated this soil property in the Chromusterts.