Ammonia borane (AB) hydrolysis is a potential process for on-board hydrogen generation. This paper presents isothermal hydrogen release rate measurements of dilute AB (1 wt%) hydrolysis in the presence of carbon supported ruthenium catalyst (Ru/C). The ranges of investigated catalyst particle sizes and temperature were 20-181 mu m and 26-56 degrees C, respectively. The obtained rate data included both kinetic and diffusion-controlled regimes, where the latter was evaluated using the catalyst effectiveness approach. A Langmuir-Hinshelwood kinetic model was adopted to interpret the data, with intrinsic kinetic and diffusion parameters determined by a nonlinear fitting algorithm. The AB hydrolysis was found to have an activation energy 60.4 kJ mol(-1), pre-exponential factor 1.36 x 10(10) mol (kg-cat)(-1) s(-1), adsorption energy -32.5 kJ mol(-1), and effective mass diffusion coefficient 2 x 10(-10) m(2) s(-1). These parameters, obtained under dilute AB conditions, were validated by comparing measurements with Simulations of AB consumption rates during the hydrolysis of concentrated AB solutions (5-20 wt%), and also with the axial temperature distribution in a 0.5 kW continuous-flow packed-bed reactor. (C) 2009 Elsevier B.V. All rights reserved.