The paper deals with on-board planning for a satellite swarm via communication and negotiation. We aim at defining individual behaviours that result in a global behaviour that meets the mission requirements. We will present the formalization of the problem, a communication protocol, a solving method based on reactive decision rules, and first results. Categories and Subject Descriptors H.4 [Information Systems Applications]: Miscellaneous; I.2.8 [Artificial Intelligence]: Problem Solving, Control Methods, and Search—Plan execution, formation, and generation; I.2.11 [Artificial Intelligence]: Distributed Artificial Intelligence—Coherence and coordination General Terms Algorithms Keywords Multiagent systems, Cooperative distributed problem solving, Task and resource allocation, Coordination, Cooperation and teamwork