Laboratory stirrer for liquids of low to medium viscosity. Able to stir up to 25 liters with reference to water with a speed range from 50 to 2000 rpm. The instrument allows continuous operation in total safety, as it is equipped with internal safety devices that stop operation in the event of any malfunctions or if working conditions are too strenuous. A progressive start avoids spillages of stirred liquids. The manufacturing materials and technologies used, allow a reliable and noiseless operation with easy of use. The compact structure, the microprocessor controlled motor and the keyless mandrel make the instrument particularly simple to use. Ergonomic design with limited size and weight.