The objective of this study was to evaluate viscosifying power of ultrasound waves on kappa carrageenan dispersions in water without using heat. After ultrasound treatment rheological characteristics of κ-carrageenan dispersions in water were evaluated at 45 °C. Shear stress-shear rate and viscosity curves clearly indicated sharp increases in viscosity and consistency coefficient (k) of ultrasound treated dispersions with ultrasonication time up to a certain level (1-2 min). All ultrasonicated dispersions showed shear thinning flow behavior. Prolonged exposure of κ-carrageenan dispersions to high-intensity ultrasonic waves produced a permanent reduction in viscosity, intrinsic viscosity and also relative molecular weight. Addition of KCl after ultrasonication was more effective in increasing viscosity compared to KCl addition prior to ultrasound treatment. Power ultrasound showed high potentials in solving some of traditional limitations related to solubility of hot water soluble biopolymers and may offer food and pharmaceuticals industries more options to benefit from a wider range of biopolymers.