Abstract: Physical and chemical analysis of the polysaccharides isolated from Hypnea musciformis (red algae) of Karachi coast showed the characteristics of k-carrageenan. The observed yield for the isolated carrageenan was about 36%. Optical rotation and sulphated ash contents were found as [α]D = 52o and 16.20%, respectively. FTIR spectra showed a characteristic band at 930 cmG1 represents the anhydrogalactose where as the band at 840 cmG1 represent the galactose-4-sulphate. Viscosity measurements revealed a linear relationship with increase in concentration and decreased with the rise in temperature of aqueous solution of carrageenan. Thermodynamic parameters such as activation energy, latent heat of vaporization, free energy change of activation and entropy change of activation was evaluated by the change in viscosity data as a function of temperature and concentration. The free energy change of activation (ΔSη) increased regularly as the concentration of aqueous carrageenan solution and temperature of the system increased. Higher values of free energy change of activation, showed the higher association of carrageenan with water at particular temperature. The values of entropy change of activation (ΔSη) of viscous flow also increased with the increase in concentration and temperature of carrageenan solution. The high negative values of entropy change of activation (ΔSη) showed that the solution of carrageenan was more ordered in initial state than the activated one.