Experiments of transient nucleate boiling are carried out on highly wetting fluids from two metallic specimen, a thick flat sample and a wire. The initial condition is controlled in terms of the system temperature as well as by a primary activation of the nucleation sites. A stepwise heat generation is investigated and the role of thermal inertia is clarified. The thermal behaviour of the system and the associated time scales are found to depend on temperature at boiling inception. This one is similar to the steady-state value for the thick flat sample but depends on the magnitude of the heating step in the case of the thin wire. (C) 2004 Elsevier Ltd. All rights reserved.