Graduated from the University of Pisa in 1861; the following year, became the assistant to the astronomer Giovan Battista Donati (1826-1873) and, in 1864, professor at the Istituto Tecnico of Bologna. In 1873, elected professor of physics at the University of Cagliari and, in 1881, succeeded his father in the chair of technological physics at the University of Pisa. Is chiefly known for his research on dynamos and electric motors. Pacinotti devised a ring inductor fitted with a collector, which became the basic component of a great number of dynamoelectric machines developed a few years later by the Belgian Zénobe-Théophile Gramme (1826-1901) and used in the manufacturing industry.