CrIIO + 4 HNVO3 CrIII(NVO3)3 + NIVO2 + 2 H2O

This is an oxidation-reduction (redox) reaction:

NV + e- NIV (reduction)

CrII - 1 e- CrIII (oxidation)

HNO3 is an oxidizing agent, CrO is a reducing agent.