Diamond electrodes with improved adhesion of the diamond layer to the electrode are produced by sandblasting a surface of the electrode body, and then non-oxidatively etching the roughened (sandblasted) surface so as to remove at least 5 μm of material from under the roughened surface. By removing at least 5 μm of material, the sand particulates in the surface of the electrode body are eliminated, and damage in the form of cracks in the electrode body which result from sandblasting is reduced or eliminated, and further, a surface metal oxide coating is not created. All of these contribute to preparing a surface where spalling of the diamond layer is less likely to occur. Concentrated phosphoric acid is an exemplary non-oxidative etchant used in the process.