Decreasing the electrolytic conductivity leads to the formation of more plentiful patterns, in comparison to normal electrochemical system. In this experiment local standing wave, cluster pattern, modulated pulse, pulse failure, pulse reflection, standing wave and pulse have been observed during the electrocatalytic oxidation of formic acid on a platinum ring electrode in a system with a very low conductivity of electrolyte and discussed. The resistivity of electrolyte used in this article is 526 Omega cm. The potential ranges of existence of different types of patterns were analysed with the help of theoretical researches and it was found that the potential ranges where different types of patterns exist can superpose each other to some extent. (c) 2007 Elsevier B.V. All rights reserved.