A statistical design of experiments (DoE) was used to evaluate the effects of CF4-O-2 plasma on Kapton films in which the duration of treatment, volume ratio of plasma gases, and microwave power were selected as effective experimental factors for systematic investigation of surface modification. Static water contact angle (theta(W)), polar component of surface free energy (gamma(p)(S)) and surface O/C atomic ratio were analyzed as response variables. A significant enhancement in wettability and polarity of the treated films compared to untreated Kapton films was observed; depending on the experimental conditions, theta(W) very significantly decreased, showing full wettability, and theta(p)(S) rose dramatically, up to ten times. Within the DoE the conditions of plasma treatment were identified that resulted in selected optimal values of theta(W), gamma(p)(S) and O/C responses. Surface chemical changes were detected by XPS and ATR-IR investigations that evidenced both the introduction of fluorinated groups and the opening of the imide ring in the plasma-treated films. (C) 2017 Elsevier B.V. All rights reserved.