The single-electron-loss cross sections for 6- 30keV B+

C+

N+ and O+impacting on H2 have been measured

for the first time

using the growth-rate method. The cross sections of B+ and C+ as functions of ion energy in the region of 6 - 30keV from the present measurements can join smoothly to those in the 100-2500keV region from previous measurements. The variations of the cross sections of B+

C+

N+ and O+ with the center-of mass energy and nuclear charge of the incident ions are well understood by the molecular-orbital theory.