I think British is sceptical, and skeptical is US. But don't get hung up on spelling. Life's too short.

Skeptical is British. Sceptical is no longer in common use and was originally the US spelling of the word. Both mean the same thing: doubtful, inclined to mistrust A word with a similar meaning you might want to look up is cynical. This other word has a more negative connotation compared to skeptical.

Australians use sceptical

skeptical is the American spelling of sceptical

brits got the spelling wrong? :P