Square pin fin minichannel heat sinks are experimentally investigated in order to find heat transfer performance of staggered and inline pin fin heat sinks. TiO2(Anatase)/H2O and TiO2(Rutile)/H2O nanofluids in volumetric concentration of 4.31% and 3.99% respectively are tested and their results are compared with distilled water. Experimentation has been performed in steady state laminar flow regime. Experimental setup is validated by comparing the results of distilled water using staggered geometry with theoretical model. The effect of geometry is also evident on enhancement ratio. Consequently, greater heat transfer enhancement is observed in staggered pin fin heat sink as compared to inline pin fin heat sink using same fluid. TiO2(Rutile)/H2O nanofluids show better thermal performance than TiO2(Anatase)/H2O nanofluids for both tested geometries. Uniform heat flux is applied at bottom side of heat sink by Mica strip heater. At a power of 192W, minimum base temperature obtained is 29.4 degrees C using TiO2(Rutile)/H2O nanofluid with staggered pin fin heat sink. (C) 2015 Elsevier Ltd. All rights reserved.