The paper presents some results of studying different types of the multi-peak oscillations and the chaotic behavior in the low-dimensional dynamical systems with a hierarchy of characteristic times. Under study is a kinetic model which consists of three nonlinear ordinary differential equations with fast, intermediate, and slow variables and illustrates that the influence of adsorbed species on the rate of catalytic reaction may lead to multi-peak oscillations and even to chaotic behavior under isothermal conditions. Such a situation occurs, for example, when the surface heterogeneity of the catalytic sites causes the activation energy of some reaction stage (or stages) to change with the surface coverage by one of the intermediate substances. Numerical simulations are used to demonstrate different types of the multi-peak oscillations and chaos in the kinetic model of hydrogen oxidation on nickel catalyst. (C) 2015 Elsevier B.V. All rights reserved.