Balance each half-reaction with respect to oxygen by adding, for each deficient oxygen, two OH- ions to the side deficient in oxygen and one H₂O molecule to the other side ( 2OH^- minus H₂O give one O atom, the net effect is to add one oxygen atom to the deficient side).

In this case, in the oxidation half-reaction, the left side need one O atom to balance oxygen, to accomplish this, add 2OH^- on the left and 1H₂O on the right. Similarly for reduction half-reaction, it needs seven O atoms on the right side so 7H₂O are added to the left and 14OH^- to the right.