The traps at the interface of directly bonded silicon-on-insulator structures have been investigated for the first time using a contactless and nondestructive computer controlled microwave transient photoconductivity method. It is shown that during bonding process electrically active states appear at the interface. The values of activation energies and capture cross-sections of charge carriers are obtained which are associated with the presence of the interface states similar to those at the Si/thermal oxide interface.