Partial molar volume, V0, of Ciprofloxacin in water, 0.05mol Kg-1 hydrochloric acid and 0.05 mol Kg-1, Iron (III) chloride solutions at 298.15 and 308.15 K was calculated fromprecision densities obtained fromDensity Sound Analyzer (DSA 5000). The data represent the smaller volume of drug in 0.05 mol Kg-1 Iron (III) chloride solution than water and 0.05 mol Kg-1 hydrochloric acid at constant temperature. The differences in volumes are interpreted as due to hydrophobicity of solutes. Relative hydrophobicities were estimated from volumes of transfer fromone media to another media. The hydrophobicity of this compound also plays a key role in the drug action. The possible mechanism of drug binding with the membrane structure is also discussed.