Biofilm infections in chronic wounds are common and pose a significant clinical challenge. This challenge was addressed by developing the SoftOx Biofilm Eradicator (SBE) composed of hypochlorous acid and acetic acid with strong broad-spectrum antimicrobial activity. First-in-human study investigating the safety and tolerability as primary endpoints, wound size effect and antimicrobial efficacy as secondary endpoints of SBE treatment in chronic leg wound patients. The study was divided into two: a randomized, double-blinded, Single Ascending Dose (SAD) phase (n=16 SBE; n=4 placebo), where patients were treated with SBE or saline (placebo) only once, followed by an open label, Multiple Ascending Dose (MAD) phase (n=8), where patients were treated with SBE once-daily or twice-daily over five days. Reporting according to CONSORT guidelines. SBE was safe and well-tolerated in chronic leg wound patients. There were no significant differences in pain during and after treatment with SBE or the placebo. The SBE treatment reduced bioburden in wounds compared to baseline, with 98 % and 49 % median reduction after SBE or placebo treatment, respectively. A dose dependent trend in absolute wound size reduction was observed in the MAD groups with a median (min, max) change of -2.99 (-14.25, -1.5) cm2 in the once-daily and -10.48 (-17.95, -0.38) cm2 in the twice-daily group, respectively. This study demonstrated the safe use of hypochlorous acid-based SBE in chronic leg wounds with promising trends of immediate antimicrobial action and beneficial effect on wound healing.