Cold atmospheric plasmas (CAPs) have become great challenge due to their vast potentialfor biomedical applications. Theresearch activities in the biological field range from the study of wound healing, cancer treatment, dentistry, sterilization and decontamination,treatment of implants for biocompatibility, dermatology and cosmetics. The biological effects of CAP are strongly linked to generation of reactive oxygen and nitrogen species (RONS). An important issue in application of CAP for tissue treatment concerned the penetration of RONS into biological tissue. RONS distribution and penetration can vary from tissue to tissue and, depending on their concentration, the biological effect can be beneficial or deleterious.In the present work, an agarose gel phantom is used as surrogates of human skin tissue to study its barrier effects on transportation and distribution of RONS after CAP treatment. We showed how the plasma conditions such as the gap distance, the treatment time and thehigh voltage frequency influence the RONS deposition, distribution and diffusion through the target. We also developed a new technique to visualize and quantify the local acidification induced by CAP treatment. These data together with our plasma source characterizationhelp us to determine safe treatment parameters for cosmetic application of CAP on the skin. This work was supportedby Cosmetosciences, a global training and research program dedicated to the cosmetic industry, located in the heart of the Cosmetic Valley, this program led by University of Orléans through the Région Centre-Val de Loire, France