Is it possible to use a tuple as a key in a Python dictionary?

Yes, a tuple can be used as a key in a Python dictionary if it consists of immutable (hashable) elements. Dictionary keys must be hashable objects, and tuples are hashable if all their elements are also hashable.

Example:

my_dict = {('a', 1): 'value1', (2, 3): 'value2'}
print(my_dict[('a', 1)])  # Outputs: value1

If the tuple contains mutable objects, such as a list, then such a tuple cannot be used as a key — it will result in a TypeError.