Display omitted •A potential energy surface for the lowest 2A′ state of LiHO+ is constructed.•The ab initio energy points are extrapolated to the complete basis set limit.•The O + LiH+ reaction are investigated using the quasiclassical trajectory method.•The reaction mechanism ruling the O + LiH+ reaction changes with collision energy. A potential energy surface (PES) for the lowest 2A′ state of LiHO+ is constructed using ab initio calculations. The MRCI method with AVQZ and AV5Z basis sets is employed during the calculations. The artificial neural network is utilized to fit the analytical PES based on 28,552 energy points which are extrapolated to the complete basis set limit. The reaction dynamics of the O + LiH+ ⟶ Li+ + HO reaction is investigated by means of quasi-classical trajectory method. The dynamics results show that the reaction mechanism dominating the title reaction changes from indirect to direct mechanism with increasing collision energy.