It’s extremely common in Europe. I regularly get messages with “15h”, “22h”, etc, but spoken is a bit of a mixed bag, you can usually use 12 hour time and know if it’s AM/PM from context, but sometimes you need to be specific.

Though the weirdest thing I’ve had to learn in Germany about time is, near where I live it’s common to say “one/three quarters [hour]”, instead of “quarter past/to [hour]”, so 10:15 is “one quarter 11”, and 10:45 is “three quarters 11”. It makes a little more sense when you know that “half 11” mean “half to 11”, not “half past” like is typical in English.