TC-HAT: a novel toolbox for the continuation of periodic trajectories in hybrid dynamical systems. This paper describes the underlying formulation and functionality of the newly developed software program TC-HAT, to perform bifurcation analysis of systems in which continuous-in-time dynamics are interrupted by discrete-in-time events, often referred to as hybrid dynamical systems. Boundary-value-problem formulations corresponding to single- and two-parameter continuations of periodic trajectories and selected associated codimension-one bifurcations in such systems are presented. Finally, the capabilities of the program are illustrated by performing bifurcation analysis of a few example hybrid dynamical systems.