TKs (tyrosine kinases) dissolved in liquids were exposed to gas plasma, and a drastic reduction of their activity was observed. Hypothesizing that this was due to gas plasma-generated ROS, plasma-treated TKs were analyzed by high-resolution mass spectrometry for the type and quantity of oxPTM types using an in-house database. Preferred oxidation targets were identified as sulfur-containing and aromatic amino acids. OxPTMs were detected on amino acid residues that have important structural or catalytic functions in TKs, such as the ATP binding site, but also on amino acid residues that are targets for therapeutic applications, such as TK inhibitors. TK dissolved in liquids were exposed to gas plasma, and a drastic reduction of their activity was observed. Hypothesizing that this was due to gas plasma-generated ROS, plasma-treated TKs were analyzed by high-resolution mass spectrometry for the type and quantity of oxPTM types using an in-house database. Preferred oxidation targets were identified as sulfur-containing and aromatic amino acids. OxPTMs were detected on amino acid residues that have important structural or catalytic functions in TKs, such as the ATP binding site, but also on amino acid residues that are targets for therapeutic applications, such as TK inhibitors.