The complexity theory and algorithms topic focuses on the theoretical foundations of parallel computing, especially the exploration of fundamental problems and issues from an algorithmic perspective and the formulation, investigation and evaluation of the appropriate computational models that allow such issues to be addressed in a rigorous, quantitative manner. Following a thorough reviewing process in which each paper was assessed by four referees, two papers have been selected for presentation as regular papers. An additional paper that was originally submitted to Topic 09 (and accepted as a research note) was also moved to this session for presentation. The committee would like to extend its sincere thanks to all those who contributed papers and to the many colleagues who helped with the reviewing process.