This book constitutes the refereed proceedings of the Second International Symposium on Parallel and Distributed Processing and Applications, ISPA 2004, held in Hong Kong, China in December 2004.The 78 revised full papers and 38 revised short papers presented were carefully reviewed and selected from 361 submissions. The papers are organized in topical sections on parallel algorithms and systems, data mining and management, distributed algorithms and systems, fault tolerance protocols and systems, sensor networks and protocols, cluster systems, grid applications and systems, peer-to-peer and ad hoc networking, grid scheduling and algorithms, data replication and caching, software engineering and testing, grid protocols, context-aware and mobile computing, distributed routing and switching protocols, cluster resource scheduling and algorithms, security, high performance processing, networking and protocols, artificial intelligence systems, hardware architecture and implementations, high performance computing architecture, and distributed systems architecture.