In the present work thermal performance of Direct Absorption Solar Collector (DASC) with TiO ₂ -water (nanofluid) as working fluid was investigated experimentally. DASC utilizes the principle of volumetric absorption i.e. solar energy absorbed by a thin film of working fluid flowing over the collector plate. The experimental study was carried out in four phases; in first phase flow rate was kept 2 lpm and volume fraction of nanofluid was changed from 0.001% to 0.007%, in second and third phase same procedure was followed for 2.5 lpm and 1.5 lpm flow rates respectively. In fourth phase the experiment was carried out with water for 1.5 lpm, 2 lpm and 2.5 lpm and the performance of collector was analyzed. Results obtained suggest that for water as a working fluid, thermal performance of the DASC at 2 lpm was better. Secondly, when nanofluid was used as a working fluid, thermal performance of the collector was found better for 0.005% volume concentration.