A high-frequency ozone generator Ozonix (Biozonix GmbH, Germany) is classified as a medical ozone generator, thus its therapeutic effects have, so far, been attributed exclusively to ozone effect. The operative principle of the device and ozone production through a dielectric barrier discharge using glass electrodes filled with a noble gas requires presence of additional physical and chemical factors, besides ozone, in the treatment field during the procedure. The purpose of the study was to determine the physical and chemical properties in the treatment field of the said device. For that purpose, measuring of emission spectra, electric and magnetic values as well as changes in surface temperature on tissue samples, as functions of the selected intensity and exposure time, was conducted, and two basic application modalities (contact discharge and air gap discharge) were used. Materials and Methods: Optical emission spectroscopy was used to record the spectrum of a plasma electrode’s glow discharge, a micro discharge occurring in the aerial interspace (air gap) between the electrode and the targeted surface and the spectrum of the discharge through a liquid medium on the surface of the tissue sample. By measuring electromagnetic values present in the treatment field, physical values of electric and magnetic fields were recorded, as well as currents passing through the treatment field. Thermographic measurements were used to record temperature changes at different intensities (10-100%) and exposure durations (30, 60, 90 and 120 seconds). Results: In the treatment field, two main emission spectra were recorded. Spectral lines of plasma electrode’s glow discharge were recorded in the optical range between 540 and 940 nm, which were identified as atomic lines of neon (Ne I) and oxygen atoms (O I). This spectrum is observed in all treatment modalities. During the formation of micro-discharges in the air gap between the electrode and the treated surface, spectral lines were recorded in the optical range between 290 and 440 nm, which were identified as molecular lines of N2 and N2+. On the tissue samples (pork skin), as a function of output intensity (10-100%), electrical values were recorded by use of oscilloscope and low impedance (Uin = 100) probe: RMS voltage (22-95 mV), RMS current (0,22- 0.95 mA). These values were used to calculate current density (4-19 μA/mm2) as well as power (5-65 μW). Using the same duration periods as the ones used in the examination of temperature change at the tissue surface (30-120 sec), the values of committed (delivered) energy were estimated (0,14-10,75 mJ). Magnetic fields were recorded at two frequency ranges. In the frequency range of 33 kHz, magnetic field was recorded in both treatment modalities as a function of intensity (10-100%) for direct contact discharge H(1,93 ± 0,59 A/m), B (2,43 ± 0,75 μT), f (32151 ± 985Hz) and air gap discharge H (2,5 ± 0,52 A/m), B (3,14 ± 0,65 μT), f (34526 ± 833 Hz). Only in the case of micro-discharge formation in the air gap were additional peaks of magnetic field observed in a wide frequency range from 40 to above 400 MHz. Due to the low intensity, magnetic field values were calculated only for 41.5 MHz peak, where H field was 0,032 ± 0,014 A/m and B field was 40 ± 17,4 nT. At 10 mm distance from plasma electrode surface, electric field strength was recorded in the range from 248 to 586 V/m depending on the selected intensity (10-100%). During the treatment, a mild increase of temperature on the surface of the tissue samples was recorded (2,6-12,2°C) as a function of intensity (20-100%) and exposure time (30-120 seconds). Conclusion: The results of the conducted research confirm the presence of mildly ionized cold atmospheric plasma in the treatment field during air gap discharge. In both treatment modalities, the presence of light in visible red and near infrared spectra, electric field, magnetic fields, the currents flowing through the tissue and mild heat generated on the surface of the tissue sample were confirmed in the treatment field. Furthermore, a significant difference was determined in the values of physical properties with respect to the application modality, where the values of temperature increase and magnetic field strengths are significantly higher in the air gap modality whilst the values of electric current (and other derived values) are lower compared to direct contact modality. According to the results of this research, it can be concluded that treatment effects with the tested devices must be attributed not only to ozone, but to cumulative effects of all physical and chemical factors, the presence of which was recorded in the treatment field during this research.