Abstract: This study describe the basic tools like viscosity measurements and thermodynamic parameters of the polysaccharide isolated from Hypnea musciformis (red algae) of Karachi Coast (Pakistan) showed characteristics of κ-carrageenan. An IR spectrum showed a fairly sharp band at 1210, 1225 cm-1 corresponding to sulphate ester and is in accordance with the high sulphate content of κ-carrageenan. Viscosity measurements revealed a linear relationship with increase in concentration and decreased with the rise in temperature of aqueous solutions of κ-carrageenan. Thermodynamic parameters were determined by the change in viscosity data as a function of temperature and concentration. The free energy change of activation (ΔGη) increased regularly as the concentration of aqueous κ-carrageenan increased, as well as rises in temperature. Higher values of free energy change of activation, (ΔGη) showed the higher association of κ-carrageenan with water at given temperature. The values of entropy change of activation (ΔSη) of viscous flow also increased with the increase in concentration and temperature of aqueous κ-carrageenan solution. The high negative values of entropy change of activation (ΔSη) showed that the solution of κ-carrageenan was more ordered in initial state than the activated one.