We give an explicit representation of the fundamental solution to the heat equation in a half-space of \({{\mathbb {R}}}^N\) with the homogeneous dynamical boundary condition, and obtain upper and lower estimates of the fundamental solution. These enable us to obtain sharp decay estimates of solutions to the heat equation with the homogeneous dynamical boundary condition. Furthermore, as an application of our decay estimates, we identify the so-called Fujita exponent for a semilinear heat equation in the half-space of \({{\mathbb {R}}}^N\) with the homogeneous dynamical boundary condition.
