For parabolic PDEs, we present a new certainty equivalence-based adaptive boundary control scheme with a least-squares identifier of an event-triggering type, where the triggering is based on the size of the regulation error (as opposed to the identifier updates being triggered by the estimation error, or the control changes being triggered by the regulation error). The scheme guarantees exponential convergence of the state to zero in the 2 L norm and a finite-time convergence of the parameter estimates to the true values of the unknown parameters. The scheme is developed for a specific benchmark problem with Dirichlet actuation, where the only unknown parameters are the reaction coefficient and the high-frequency gain. For this specific problem, no existing adaptive scheme can handle the unknown high-frequency gain. An illustrative example allows the comparison with other adaptive control design methodologies.Keywords: parabolic PDEs, boundary feedback, backstepping, adaptive control. Recently, the scope of adaptive controllers has been extended to more complicated cases: parabolic PDEs with input delays (see [11]) and parabolic PDEs with distributed parameters and inputs (see [27]). Moreover, adaptive controllers have been used extensively for hyperbolic PDEs: see [1][2][3][4][5][6][7][8][9][10]20].The purpose of the present work is the development of a novel adaptive boundary control scheme for parabolic PDEs. The proposed methodology is based on the extension to the parabolic infinite-2 dimensional case of the recently proposed adaptive control scheme in [17] for finite-dimensional systems. It is a certainty-equivalence adaptive scheme with a least-squares, regulation-based identifier. The proposed adaptive boundary control scheme guarantees exponential convergence of the state to zero in the 2 L norm. Moreover, the scheme guarantees a finite-time convergence of the parameter estimates to the true values of the unknown parameters. The adaptive scheme is developed for a specific benchmark problem with Dirichlet actuation, where the only unknown parameters are the reaction coefficient and the high-frequency gain. For this specific problem, no other adaptive scheme can handle the unknown high-frequency gain. It should be noticed that the proposed adaptive design can be extended to more complicated cases as well as to systems of parabolic PDEs.An advantage of the certainty-equivalence adaptive boundary control scheme with regulationbased, least-squares identifier is that it can be combined with all methodologies of static boundary feedback design for parabolic PDEs. More specifically, the proposed scheme can be combined with: i) the backstepping design (see [22,31]), and ii) the reduced model design (see [12,25]). The derivation of the adaptive control scheme does not require the knowledge of a Lyapunov functional for the parabolic PDE.It should be noted that the closed-loop system under the proposed adaptive control scheme is a hybrid infinite-dimensional system. The study of hybrid (event-triggered) distributed...