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Purpose - The purpose of this paper is to study the corrosion resistance and the insulating characteristics of an environment-friendly chromium-free coating on electrical steel. Design/methodology/approach - A water-based semi-inorganic environment-friendly insulating coating on electrical steel was developed. The coating system of silane coupling agent and rare earth salt were used first in this coating to replace the chromate containing coating. In this study, it provided a successful combination of coating and passivation. Findings - Several test results, such as insulating ability, corrosion resistance, adhesion strength and hardness, showed that the performance of the film complied fully with the industry standards, particularly excellent in its corrosion resistance and the maximum corrosion resistance (neutral salt-spray test) time up to 20 h. Originality/value - There have been few reports on the chromium-free insulating coating on electrical steel, and described in the paper, this environment-friendly insulating coating on electrical steel was found to be highly effective.