I recently installed LyX for MacOS and it’s pretty neat, specially for us LaTeX users because it makes it so easy to produce LaTeX-quality documents in no time. If you want to make a brief report on some topic you’re researching, or a quick draft, it’ll save you a fair amount of time instead of using your regular TeX editor. However, when I wanted to check the spelling it produced the following warning LyX: failed to start ispell. What happens is that the GNU package ispell was not installed in my system. Therefore the appropriate solution is to install it.
If you have macports, simply open a terminal and write:
sudo port install ispell
I guarantee it’ll work.