Evening twilight airglow emissions of OH (7,2) band and Li 6708 Å are observed by Dunn-Manring type photometer and following important results are obtained.(i) Intensity of OH (7,2) and Li (6708 Å) decrease exponentially during evening twilight period. (ii) OH (7,2) band covaries with Li (6708 Å) during evening twilight period. (iii) Empirical equations of OH (7,2) band with time is obtained. (iv) Possible explanations of such type of variations is also presented.