Ab initio potential energy curves and transition dipole moments have been calculated for the X-2 Sigma(+), A (2)Pi and B' (2)Sigma(+) states of MgH using the multi-reference configuration interaction method with large active space and basis sets. Accurate transition dipole moments are reported at Mg-H distances from 2.2 a(0) to 20 a(0), and they can be combined with the available experimental data on MgH ( analytic and Rydberg-Klein-Rees potential energy curves for the X (2) Sigma(+), A (2)Pi and B' (2) Sigma(+) states), to calculate the Einstein A coefficients for all rovibronic transitions of MgH appearing in solar and stellar spectra. (c) 2012 Elsevier B.V. All rights reserved.