Introduction: When a gas is used for therapy, often the kinetic behavior and their distribution in biological systems is not known, leading to unsatisfactory results for clinical application. The use of ozone in living organisms has been scientifically released worldwide under the name of ozone therapy. The efficacy of this technique is determined primarily by the diffusion of gas within the tissues or fluids and which determines their action in the entire target region. We propose the development of technique to monitoring the O3 dissolved in the biological fluid using an optical device operating in the red-infrared region. Methods: The recombination of O3 in O2 enables the monitoring of the latter by the measurement of SpO2, and, based on this phenomenon, we propose to use an optical device operating in the red-infrared region to monitoring indirectly the diffusion of O3 in fluids. The system was based on optomechanical arrangement using a capsule containing fluid that was ozonated or oxygenated during the process. A pulse oximeter is a noninvasive device used for continuously measure of SpO2 resulting from the recombination of ozone. Results: The measurements of SpO2 when subjected to ozone and oxygen, showed an increased rate of SpO2 function of time for both cases reaching its peak in 80s and 160s, respectively. The experimental data concerning the SpO2 saturation as a function of time can be fitted by the theoretical model, showing a good correlation between them. Conclusion: A technique was developed using an optical device operating in the red-infrared region to monitoring ozone dissolved in biological fluid, showing a simple and effective way to indirectly monitoring the presence of ozone in fluids.