The electrical voltage in Mexico is 110-120 volts, the same as in the United States. While the sockets are the standard two prong versions that are found in the United States and Canada, adapters may be required for certain equipment.
The main reasons for adapters are grounding and polarization. Sockets often lack the capacity to accommodate a grounded plug and an adapter should be brought specifically to make the change from three prongs to two.
Polarization is most often found when one blade of a plug is taller than the other, making it impossible for it to be inserted upside down. Since this isn´t a requirement in Mexico, these plugs will not fit in a standard socket without a proper adapter.