The basics and experimental details of transmission radiation techniques in the application to conservation of wooden cultural objects are described. Standard and synchrotron X-rays, as well as neutrons, can provide very useful options for the non-invasive analysis of the wood structure, its conservation state and the influence of wood treatment in the conservation and decontamination process. The working and application range specific to each kind of radiation is discussed. Although X-ray methods (standard tube systems and synchrotron light source facilities) can cover a wide range in object size and wood density, neutrons can be used preferentially to study and quantify substances with high hydrogen content (moisture, resin, glues, wax) inside the wooden structure. Several examples chosen from studies performed within COST Action IE0601 illustrate the results that can be obtained using these techniques and their combination. The need for further studies using the performances available at large-scale facilities is discussed as a way to establish routine approaches for wood conservation and museums objects.