.THMX File Extension

Microsoft Office themes consist of color, font, and effect settings that a user can quickly apply to a document. For example, a business might create a custom Office theme that consists of their brand's colors and fonts. The business could then use that theme to apply their colors and fonts to documents they create.

Prior to Office 2007, users could create themes in each Office application, but they could not apply those themes across applications. To make theming related documents, presentations, and spreadsheets easier, Microsoft created the cross-application THMX format and released it with Office 2007.

Thus, in Office 2007 and later versions, users can select and apply the same theme to a Word document, Excel spreadsheet, and PowerPoint presentation.

How to save an Office 2007 theme (THMX file)

To save an Office 2007 theme you've created as a THMX file:

1. Select either the Design tab (Word, PowerPoint) or Page Layout tab (Excel).
2. Click Themes → Save Current Theme.
3. Name and save your theme.

Where Office stores users' THMX files

In Windows, Microsoft Office stores custom THMX files in the following location:

%AppData%/​Microsoft/​Templates/​Document Themes

In macOS, Microsoft Office stores custom THMX files in the following location:

~/​Library/​Application Support/​Microsoft/​Office/​User Templates/​My Themes

To use a THMX file with Microsoft Office applications:

1. Place the THMX file in the appropriate location noted above.
2. Open a Word, Excel, or PowerPoint document.
3. Select either the Design tab (Word, PowerPoint) or Page Layout tab (Excel).
4. Click Themes.
5. Select the theme your THMX file contains.