Motives and determinants supporting inter-firm technological cooperation have been extensively investigated in developed countries but scarcely addressed in developing countries. This paper addresses these issues, investigating empirically several factors influencing the likelihood to cooperate on R&D and innovation between Argentine and Spanish firms, their strategic motives and firms characteristics which influence cooperation. We draw upon data collected through a survey of 104 firms and complementary information gathered from 19 in-depth interviews, combining both qualitative and quantitative methodology. Results of a multinomial regression and the interviews show that the probability to cooperate increases with the firm size and exportation activities and decrease with the firm age whereas, opposite to literature findings, technological intensity of the firm is a non-significant variable. While for Argentine firms the principal motives are cost reduction and the possibilities for improving learning and capabilities, access to new knowledge for technological development and the search for market opportunities are the principal motives for firms located in Spain. Results of interviews also indicates that firm-specific motives and expectations may differ considerably according the activity sector, with relevant implication for norms and regulation policies in each country.