I just did a google search and found that they can be used, but a full charge could take a long time and may overcharge if not stopped in time. I suppose the Ni-cad charger could be used (carefully) to partially charge a NiMH battery in a situation where that’s all that was available as a charger. Well, here’s a link to the source: http://www.greenbatteries.com/nimh-battery-charger-faq/#NiCD%20charger%20for%20NiMH%20batteries