Abstract. A new calibration/validation experiment for GOCE mission is proposed. Simultaneously with the satellite mission another gradiometer will be flown on the board of the stratospheric balloon on the altitude 20–40 km. The measurements can be compared with satellite data. The advantage of this method is that the same functionals are compared – gravity gradients. The post-mission external calibration/ validation is possible more directly than through the comparison with the ground truth gravity anomalies or geoid undulation. The calibrating gradiometer is less sensitive, but thanks to the altitude difference, compatible in precision with the orbiting GOCE gradiometer. Analytical procedure of the downward continuation is presented which permits comparison of these observables, supported by numerical examples. The threshold for the precision of the calibrating gradiometer is indicated. Similar comparison can be done between GOCE and GRACE missions.