Nanowires of Cu(II) 1,4,8,11,15,18,22,25-octabutoxy-29H,31H-phthalocyanine (CuPcOC₄) have been fabricated onto the glass substrate by using low cost self-assembly technique. It has been demonstrated that these nanowires were highly sensitive and selective towards Cl2 at room temperature with minimum detection limit of 5 ppb. The response of nanowires was found to increase linearly (91–670%) with increase in Cl₂ concentration (5–1500 ppb). The adsorption of Cl₂ on nanowires surface has followed Elovich equa-tion. Raman spectroscopic and XPS studies revealed that central metal ions of CuPcOC₄ molecules were the predominant sites of Cl₂ absorption. The results emphasized that these nanowires can be promising candidates for room temperature Cl₂ sensing applications.