A detailed experimental investigation on the efficiency of the power absorption of Multi-resonant Oscillating Water Column (MOWC) wave energy caissons in an array is reported. Regular wave measurements were conducted on an 1:50 scale model of an array of Multiresonant Oscillating Water Column (MOWC) type free standing wave energy caissons using the images method. A range of hydrodynamic parameters, with a different damping of Oscillating Water Column (OWC) chamber and various centre to centre spacings (S) between the caissons in an array for a constant OWC width (b), were used, i.e., experiments were conducted for different ratios. It is found that, hydrodynamic efficiency of MOWC for power absorption increases with increased value up to 3, beyond which it reduces. About 60% efficiency can be achieved with a ratio of 3 which is considered as optimum spacing. The efficiency decreases with increase in wave steepness (), due to a greater blow up period for higher values than for lower values during which the pressure becomes atmospheric. The percentage energy reflection decreases with increasing relative water depth. The average energy reflection is found to be 30%. Further investigation is recommended in order to enhance the efficiency considering the structure geometry as well as the damping of the air chamber.