Diffusion and sorption behaviors of NaCl in surimis prepared from Pacific cod (Gadus morhua), red sea bream (Pagrus major) and big-eye tuna (Thunnus obesus) were studied. The variations of Fick's diffusion coefficients, D, of NaCl with respective maxima and of almost linear sorption isotherms were consistently interpreted with the dual mode diffusion and sorption theory. Good linear correlations were found between the concentrations of Langmuir mode sorption site, Sa, of NaCl (R-2 = 0.993) and also thermodynamic diffusion coefficient of the Langmuir species, D-T(L), of NaCl (R-2 = 0.950), with charged amino acid contents in the surimis. The facts that Sa and DT(L) are related to the concentration of charged site suggest that the sites gather in a certain region, the water content of which becomes high with the site concentration. (C) 2014 Elsevier Ltd. All rights reserved.