Asst.Prof.Dr. Jessada Tariboon Oscillation of Impulsive Functional Differential Equations Department of Mathematics, Faculty of Applied Science Asst.Prof.Dr. Jessada Tariboon King Mongkut’s University of Technology North Bangkok OBJECTIVE In this research, we investigate the oscillation of a class of second-order impulsive differential equations of the form By using the equivalence transformation and the associated Riccati techniques, some interesting results are obtained. METHODOLOGY METHODOLOGY Lemma 2.1 If the second-order differential equation is oscillatory, then Eq. (1.1) is oscillatory, where Lemma 2.2 (Leighton type oscillation criteria) Assume that the functions and If and then is oscillatory. Theorem 2.3 Assume that Where Then Eq. (1.1) is oscillatory. If then and (1.1) becomes Theorem 2.4 Eq. (2.2) is oscillatory if and only if is oscillatory. Corollary 2.5 Assume that and Then Eq. (2.2) is oscillatory. RESULTS & DISCUSSION Figure 1: Time history of x(t). Acknowledgement This research work is financially supported by the Office of the Higher Education Commission, and King Mongkut’s University of Technology North Bangkok (contract no. 2555A11962006). Contact jessadat@kmutnb.ac.th Department of Mathematics, Faculty of Applied Science, King Mongkut’s University of Technology North Bangkok, Bangkok, 10800, Thailand