SummaryIn 1905 the Campos Rodrigues Observatory was founded in Lourenço Marques, the capital of Mozambique, by then part of the Portuguese overseas empire. In this paper the inception and early history of the CRO are analysed in the broader context of the interwoven history of the Portuguese and British empires in Africa, and specifically with respect to the scientific relations between Mozambique and South Africa. The equipment, personnel, practices and networks involved in the inception and early development of the CRO (...) are brought into focus in order to illustrate the problems and strategies that shaped the establishment and functioning of this observatory, which was conceived essentially as a symbol of imperial stamina and colonial prowess. It is suggested that by providing a focal point for the development of scientific relations between Mozambique and South Africa, the CRO served both Portuguese ambitions for recognition as an imperial power and the emergence of South African nationalism. (shrink)