The gas-solid flow in a three-dimensional slot-rectangular spouted bed was studied experimentally and numerically. Predictions from the coupled computational fluid dynamics and Discrete Element Method, a powerful numerical approach, are compared with experimental measurements. Flow features inside the slot-rectangular spouted bed were investigated experimentally using a pressure transducer and an optical fibre probe to obtain profiles of pressure, voidage, and particle flux. Static bed heights of 90, 120, and 150 mm of 2.85-mm diameter particles were investigated at different spouting velocities to find the bed pressure drop, flow regime, and minimum spouting velocity. For velocities exceeding the minimum spouting velocity, measured profiles of pressure, voidage, and particle flux are in close agreement with simulation predictions.