The gelation behavior of K-carrageenan in aqueous solution was studied by microdifferential scanning calorimetry and rheology. It was found that the formation and melting of tc-catrageenan hydrogels were thermally reversible and extremely sensitive to K-carrageenan concentration. In comparison with the crossover of G' and G '', the extrapolation method based on multiwave oscillation and Winter Chambon criterion were able to give more accurate critical gel temperature Te. At the gel point, the critical relaxation exponent n was almost constant whereas the critical gel strength Sg increased with ic-carrageenan concentration. In the stable gel state, the plateau modulus Ge depended on temperature according to a power -law scaling, Ge proportional to epsilon(2.2), where epsilon is the relative distance (=broken vertical bar T - T-c broken vertical bar/T-c) and independent of K-carrageenan concentration. The presence of potassium ions shifted the formation and melting temperatures of tc-catrageenan hydrogel to higher temperatures, and the temperatures for gel formation and melting increased with increasing potassium ions' content. (C) 2016 The Society of Rheology.