We prove error estimates for the wave equation semi-discretized in space by hybrid high-order (HHO) method. These lead to optimal convergence rates smooth solutions. consider first second-order formulation time, which we establish $${\varvec{H}}^1$$ and $${\varvec{L}}^2$$ -error estimates, then first-order formulation, estimates. For both formulations, semi-discrete HHO scheme has close links w...