public static void HighlightText() { WordFile wordFile = new WordFile(); WordDocument document = wordFile.Import(File.ReadAllBytes("Sample.docx")); WordDocumentBuilder builder = new WordDocumentBuilder(document); //Apply new highlight style Action <CharacterState> action = new Action <CharacterState>((state) => { state.HighlightColor = Colors.Yellow; }); //Highlight all the "Page" text in the document builder.ReplaceStyling("Page", true, true, action); File.WriteAllBytes("HighlightText.docx", wordFile.Export(document)); }