The RadOutlookBarItems expose the Icon and SmallIcon properties. They are of type BitmapSource and they define the source of the picture placed infront of the content of the RadOutlookBarItem.
The Icon property gets or sets the icon of the RadOutlookBarItem when it is in normal state – not minimized
Figure 1 : Setting Icon property
The SmallIcon property gets or sets the icon of the RadOutlookBarItem when it is in the minimized area or when it is in the ItemDropDownContent. The ItemDropDownContent is the content of the pop up which is opened after you click the overflow button located in the lower right corner of the RadOutlookBar.
Figure 2 : Setting SmallIcon property
You can see how to bind the icon properties to e property of a business object in the Data Binding example in the online SDK repository.