The problem of adaptive stabilization of a class of continuous-time and time-varying nonlinear plants is treated in this paper. The control scheme guarantees that the state of the plant, with bounded time-varying parameters, asymptotically converges to zero. For the nonlinear case with n(2) + n unknown parameters (n time-varying and n(2) constant), when the control matrix B is unknown the controller has to adjust n(2) + 1 parameters providing only local stability results. On the contrary, when the control matrix B is known only one parameter has to be adjusted and the proposed scheme provides global stability results. The general methodology is particularized for the linear case with 2n(2) unknown parameters (n(2) time-varying and n(2) constant), adjusting n(2) + 1 parameters when the control matrix B is unknown and guarantees only local stability results, where as in the case when the control matrix B is known only one parameter has to be adjusted and the proposed scheme provides global stability results. (C) 2009 The Franklin Institute. Published by Elsevier Ltd. All rights reserved.