An experimental hyperbaric system was designed and built to explore the effect of hyperbaric treatment on the respiration rate (RR) and respiratory quotient (RQ) of tomato. It consists of five containers that can be individually pressurized from 1 to 9 atmabs. The respirometer was equipped with a flow meter, control valve, pressure transducer, CO2 and O2 gas analyzer, and type T thermocouples that are all connected to a data acquisition and control card. A software interface was programmed to allow control of the air flow rate through the proportional valve of the flow meter based on a proportional–integral–derivative algorithm system. Hyperbaric treatments have been performed on tomato fruit, and it was observed that RR was inversely proportional to pressure.