Jet impingement is one of the best methods for achieving high heat transfer coefficient in a single phase and has been a topic of active research for several decades, involving both experiments and computations. Most of the research on multiple jets have been carried out for an array of jets in the high Reynolds number regime. Experimental and numerical investigations were carried out to study the effect of inline three jet array impinging on a flat plate with varying Reynolds Number. Air was considered as the cooling medium. This study investigates the fluid flow and heat transfer characteristics of circular and square jet arrays impinging orthogonally on a flat-plate with inline arrangements. The number of jets is 3. The Reynolds number is varied from 3000 to 6000. The numerical methodology is validated using the experimental local Nusselt number distribution for inline three jet array with the same geometry and boundary conditions. In this work, circular and square of equal hydraulic diameters were selected for a comparative study. The results reveal that square jet array has better heat transfer characteristics compared to a circular array. The optimum value of jet to target plate distance is 6 times the jet diameter for both circular and square jet array. Also, the optimum value of pitch to diameter ratio is 2.