The aim of the study was to determine the influence of maturation and of cooking processes on water losses and on the vitamin B12 content of meat. Three types of muscle (Longissimus lumborum, Longissimus thoracis and Triceps brachii) were sampled from a total of 16 animals, representative of animals raised for meat production in France. Three durations of maturation were compared: 1, 3 and 14 days. Different cooking processes were applied: Longissimus lumborum was deep-fat fried or roasted, Longissimus thoracis was pan fried or grilled and Triceps brachii was braised. The cooking yield averaged 55–56% for Triceps brachii, 73–77% for Longissimus lumborum and 85–87% for Longissimus thoracis. Vitamin B12 concentration in raw meat was significantly higher in Triceps brachii than in Longissimus lumborum and Longissimus thoracis (20.86, 11.53 and 9.21 ng/g wet tissue, in the same respective order). When expressed on a wet weight basis, all concentrations were significantly increased by cooking. When expressed on a lipid-free dry basis, significant losses in vitamin B12 were measured only in the braised Triceps brachii (−25%) and in the deep-fat fried Longissimus lumborum (−5.5%) as a result of long duration and high temperature of cooking, respectively. Maturation did not affect the vitamin B12 content of meat, whether raw or cooked.