The effect of added ions (0.5mM K + or 0.25mM Ca 2+ ) and temperature (25 or 60°C) on the solution properties of κ-carrageenan (0.2%, w/w) were investigated using static light scattering, circular dichroism and viscometry. At 60°C (coil conformation), added salts caused a decrease in the radius of gyration (R g ), as chains became less spatially extended. As temperatures declined (60–25°C), κ-carrageenan underwent a temperature-induced transition whereby R g decreased by ∼18% with or without added K + , and 2.7% with added Ca 2+ . Temperature dependence of the molecular ellipticity [θ] at 620nm, described by the van't Hoff relationship, estimated enthalpic changes for the unraveling of the ordered conformation of 2.3–4.1kJ/mole depending on the ionic conditions. At 25°C (ordered conformation), R g decreased and [θ] increased with added salts. No significant effect of ionic strength on intrinsic viscosity was found.