Flow vectoring by a pair of synthetic jets is suitable for modification of the global flow characteristics with practical applications in active flow control and adaptive heat convection. The interaction of a pair of synthetic jets, with a separation distance s =3.3D, stroke length L-0 = 29D, and Reynolds number Re = 300, are investigated numerically using computational fluid dynamics (CFD) and experimentally using particle image velocimetry (PIV). To achieve the most realistic calculation- of the flow induced by synthetic jets, a full unsteady RANS simulation is performed of the internal flow in two cavities as well as the external jet flow using a dynamic mesh technique. The results for the intricate flow vectoring phenomenon show a reasonable quantitative agreement with PIV measurements, with a maximum deviation from PIV measurements of 14% for stream -wise centreline velocity in 10 < y/D < 20. The effect of phase difference between the pair of jets on the vectoring of the merged jet is investigated for delta phi = 0 degrees, 60 degrees and 130 degrees. The merged jet is vectored in the direction of the cavity that is leading in phase, with a similar trend shown by the experimental and numerical results of instantaneous and time -averaged vortical structures. This leads to a better physical understanding of the fluid mechanics of adjacent synthetic jets, and will enhance the theoretical basis needed to promote their practical application. (C) 2016 Elsevier Ltd. All rights reserved.