This work shows how bibliometric techniques can partly answer the exchange evaluation among the actors of the Science-Technology-Society system. This bibliometric study was particularly focused on the evaluation of scientific collaborations by a co-authorship analysis of the Spanish actors from the public sector (representing Science) and from private sector (representing Technology) over the period 1995-1999. The studied dataset of references was collected from the databases ICYC and ISOC produced by the CINDOC. Coding processes to prepare the bibliometric analysis were applied to this dataset. The references were codified in 8 scientific and technical sectors and the affiliations of the authors were standardized and combined according to 3 levels (organizations, institutional categories, public or private categories). Some bibliometric results representing each of these 3 levels of aggregation are discussed. The bibliometric method of network analysis was used for the characterization of the regularity, the intensity and the structuring of the exchanges among organizations. In conclusion, the bibliometric results allow quantifying the exchanges among the actors of the public sector and the private sector in Spain at the national level, for scientific and technical sectors or for Autonomous Regions. The bibliometric techniques prove to be very relevant tools for the evaluation of the exchanges in the Science-Technology-Society system.