A microelectromechanical gyroscope comprising: a substrate (2; 102; 202; 302); a first outer mass (11; 111; 211; 311), a second outer mass (12; 112; 212; 312) and an inner mass (10; 110; 210; 310), all elastically coupled to the substrate (2; 102; 202; 302) to be movable in a driving direction along a first axis (X), the first outer mass (11; 111; 211; 311) and the second outer mass (12; 112; 212; 312) being arranged at opposite sides of the inner mass (10; 110; 210; 310) with respect to the first axis (X); a driving system (4, 16a, 16b, 20a, 20b; 216a, 216b, 220a, 220b; 316a, 316b, 320a, 320b), configured to oscillate the first outer mass (11; 111; 211; 311) and the second outer mass (12; 112; 212; 312) along the first axis (X) in phase with one another and to oscillate the inner mass (10; 110; 210; 310) along the first axis (X) in phase opposition with the first outer mass (11; 111; 211; 311) and the second outer mass (12; 112; 212; 312); the first outer mass (11; 111; 211; 311), the second outer mass (12; 112; 212; 312) and the inner mass (10; 110; 210; 310) being provided with respective sets of sensing electrodes (17a, 21a; 117a, 121a; 217a, 221a; 317a, 321a), configured to be displaced in a sensing direction along a second axis (Y) perpendicular to the first axis (X) in response to rotations of the substrate (2; 102; 202; 302) about a third axis (Z) perpendicular to the first axis (X) and to the second axis (Y); the inner mass (10; 110; 210; 310) comprising a first inner mass portion (10'; 210') and a second inner mass portion (10"; 210") rigidly coupled to one another; characterized in that the first inner mass portion (10'; 210') is symmetric with respect to the first outer mass (11; 211); and the second inner mass portion (10"; 210") is symmetric with respect to the second outer mass (12; 212). a substrate (2; 102; 202; 302); a first outer mass (11; 111; 211; 311), a second outer mass (12; 112; 212; 312) and an inner mass (10; 110; 210; 310), all elastically coupled to the substrate (2; 102; 202; 302) to be movable in a driving direction along a first axis (X), the first outer mass (11; 111; 211; 311) and the second outer mass (12; 112; 212; 312) being arranged at opposite sides of the inner mass (10; 110; 210; 310) with respect to the first axis (X); a driving system (4, 16a, 16b, 20a, 20b; 216a, 216b, 220a, 220b; 316a, 316b, 320a, 320b), configured to oscillate the first outer mass (11; 111; 211; 311) and the second outer mass (12; 112; 212; 312) along the first axis (X) in phase with one another and to oscillate the inner mass (10; 110; 210; 310) along the first axis (X) in phase opposition with the first outer mass (11; 111; 211; 311) and the second outer mass (12; 112; 212; 312); the first outer mass (11; 111; 211; 311), the second outer mass (12; 112; 212; 312) and the inner mass (10; 110; 210; 310) being provided with respective sets of sensing electrodes (17a, 21a; 117a, 121a; 217a, 221a; 317a, 321a), configured to be displaced in a sensing direction along a second axis (Y) perpendicular to the first axis (X) in response to rotations of the substrate (2; 102; 202; 302) about a third axis (Z) perpendicular to the first axis (X) and to the second axis (Y); the inner mass (10; 110; 210; 310) comprising a first inner mass portion (10'; 210') and a second inner mass portion (10"; 210") rigidly coupled to one another; characterized in that the first inner mass portion (10'; 210') is symmetric with respect to the first outer mass (11; 211); and the second inner mass portion (10"; 210") is symmetric with respect to the second outer mass (12; 212). <EOS>