This paper reports on the viscosity and density study of the 1,4,7,10,13 pentaoxcyclopentadecane (15C5) as binary system and 15C5 in present of KBr (the ternary system) in aqueous solutions at 25oC. The results of the viscosity and density depend on type of system, and concentration rang. The relative viscosity obtain was fitted well by the use of Jones-Dole and Falkenhagen equations to the viscosity parameters i.e. the apparent molar volume and the effective rigid molar volume at infinite dilution. The results indicate that 4.2 mole of water are engaged in one mole of 15C5 and the complexation volume 0.015 dm3mol-1 K+ with 15C5 has been determine. The results are interpreted in terms of molecular and occupation of crown ether cavity by solvent molecules.