The luminescence properties of CaMoO4:Pr3+ have been investigated in different experimental conditions in order to obtain information on the excitation and de-excitation pathways of this system. The structure of the emission spectrum depends on different factors: excitation conditions, doping level, temperature, etc. In addition, measurements carried out on single crystals and on micro- or nano-crystalline powders obtained by solid state reaction and sol-gel method have revealed that the morphology of the sample, and then the concentration of the lattice defects, strongly influences the excitation mechanism. These effects have been analysed in the light of available models and a general scheme accounting for the experimental observations has been proposed