The first European meteorological polar-orbit satellite MetOP-A is scheduled to launch on 17 July 2006, and it will carry both heritage instruments from NOAA and a new generation of European instruments with improved sensing capabilities for both weather and climate applications. Both the High-resolution Infrared Radiation Sounder (HIRS) and Infrared Atmospheric Sounding Interferometer (IASI) measure infrared radiation emitted from the atmosphere and surface, and their data will be used for calculating the atmosphere's vertical temperature profile, retrieving geophysical parameters such as ocean surface temperatures, total column ozone, precipitable water, and cloud height and coverage, as well as direct radiance assimilation for numerical weather prediction. In contrast to the traditional broad band infrared sounder HIRS, IASI will be the first operational space-based interferometer that covers 645-2760 cm-1 at 0.25 cm-1 resolution with no spectral gap. This study will assess the on-orbit radiometric, spectral, and spatial accuracy of the infrared sounders on MetOP-A by cross comparison of radiances between instruments involving HIRS, IASI, and the Atmospheric Infrared Sounder (AIRS), as well as comparison with forward calculations at validation sites. Early results from on-orbit verification will be presented, and the impact of instrument performance on applications will also be evaluated.