Changes in microstructure of Zr, Ti, and Ti-6%Al-%V resulting from ion-beam sputtering used to prepare samples for transmission electron microscopy have been correlated with hydrogen absorption. Zr was particularly sensitive to this phenomenon, resulting in extensive hydride formation in thin foil samples. Hydrogen enrichment extending to several micrometers in depth could also be produced in bulk samples in a few hours of sputtering. The performance of various sputtering units in different configurations has been examined. It is concluded that hydride formation appears to be caused primarily by the presence of hydrocarbons, for example, from the backstreaming of diffusion pump oil, in the residual vacuum background of the sputtering chamber.