Abstract: Cold atmospheric plasma (CAP) devices generate an ionized gas with highly reactive species and electric fields at ambient air pressure and temperature. A flexible dielectric barrier discharge (DBD) was developed as an alternative antimicrobial treatment for chronic wounds. Treatment of Staphylococcus aureus in collagen-elastin matrices with CAP for 2 min resulted in a 4 log reduction. CAP treatment was less effective on S. aureus on dermal samples. CAP did not affect cellular activity or DNA integrity of human dermal samples when used for up to 2 min. Repeated daily CAP treatments for 2 min lowered cellular activity of dermal samples to 80% after 2 to 4 days, but this was not significant. Repeated treatment of ex vivo human burn wound models with CAP for 2 min did not affect re-epithelialization. Intact skin of 25 healthy volunteers was treated with CAP for 3× 20” to determine safety. Although participants reported moderate pain scores (numerical rating scale 3.3), all volunteers considered the procedure to be acceptable. Severe adverse events did not occur. CAP treatment resulted in a temporarily increased local skin temperature (≈3.4°C) and increased erythema. Lowering the plasma power resulted in a significantly lower erythema increase. Good log reduction (2.9) of bacterial load was reached in 14/15 volunteers artificially contaminated with Pseudomonas aeruginosa. This study demonstrated the in vitro and in vivo safety and efficacy in bacterial reduction of a flexible cold plasma device. Trial registration number NCT03007264, January 2, 2017 Key Points: • CAP strongly reduced bacterial numbers both in vitro and in vivo. • Re-epithelialization of burn wound models was not affected by repeated CAP. • CAP treatment of intact skin was well tolerated in volunteers.