MEC can refer to:
- Businesses
- Mitsubishi Electric Corporation, a Japanese Mitsubishi Group core company
- Morgan Electro Ceramics, a ceramics manufacturing company
- Mongolia Energy Corporation, a mining company
- Mountain Equipment Co-op, a Canadian outdoors gear & clothing store
- Myanmar Economic Corporation, a Burmese military-owned corporation
- MEC (media agency), a media agency network based in London and New York
- Education
- The Ministry of Education of Brazil
- The Ministry of Education, Social Policy and Sport of Spain
- Midland Empire Conference, a high school activity conference whose members are located in Missouri, USA
- Manufacturing Engineering Centre, Cardiff University, United Kingdom
- Model Engineering College, an engineering college in Thrikkakara, Kerala, India
- Master in Economics
- Politics
- Member of the European Commission, a member of the European Union's executive body
- Model European Council, a political simulation between the European Schools
- Member of the Executive Council, a member of the South African provincial government
- Ministry of Education (Brazil), the Brazilian education ministry
- Transportation
- Maine Central Railroad, a railroad in central and southern Maine, USA
- Manta Air Base (IATA airport code), Manta, Ecuador
- Other
- Marginal efficiency of capital, an economics theory that links investment to interest rates
- Mary Ellen Carroll, a conceptual artist who lives and works in New York City
- An alternate name for Metz in the Bulgarian, Serbian, and Russian languages. See List of European cities with alternative names
- Mec, Poland
- Media Expansion Card, a type of PCIe computer expansion card
- Microbial Electrolysis Cell, a type of bioelectrochemical system
- Middle Eastern Coalition, a fictional faction in the computer game Battlefield 2, Battlefield 2: Modern Combat and Battlefield Bad Company
- Mountain East Conference, a U.S. college athletic conference set to begin play in 2013
- Munitions and explosives of concern, explosives that did not explode when they were employed
- In pharmacology, the minimal effective concentration, i.e., the smallest concentration of a drug that will induce the desired pharmacological effect.
- Mandatory Editorial Coordination, a peer review process used by the IEEE
- Measured Environmental Concentration