Abstract Unsteady MHD free convection and mass transfer from a viscous, incompressible, electrically conducting and heat absorbing fluid flow past a vertical infinite flat plate is investigated. The flow is induced by a general time-dependent movement of the vertical plate, and the cases of ramped temperature and isothermal plates are studied. Exact solutions of the governing equations are obtained. The Sherwood number, Nusselt number and skin friction coefficients are obtained for both ramped temperature and isothermal plates. Some applications of practical interest are discussed for different types of plate motions. The numerical values of species concentration, fluid temperature and fluid velocity are displayed graphically whereas the numerical values of Sherwood number, the Nusselt number and skin friction are presented in tabular form, for different parameter values for both ramped and isothermal plates.