In this paper is presented the measurement of the muon mean lifetime using as source muons generated by the interaction of cosmic rays with the atmosphere. The experimental setting consists of an array of three scintillator plates coupled to photomultiplier diodes. Events in which a moun passes through the two upper plates, loses all of its energy and decays in the lower plate were recorded. The measurement of the time difference between the signal produced in the upper plates and the lower plate gave 916 valid events. From the parametrization of their distribution was obtained a mean lifetime (2.19 ± 0.09) µs. This value is compatible with the world average value (2.1969811 ± 0.0000022) µs