This book constitutes the refereed proceedings of the 16th International Symposium on Advanced Parallel Processing Technologies, APPT 2025, held in Athens, Greece, during July 13-16, 2025.

The 17 full papers and 10 short papers included in this book were carefully reviewed and selected from 74 submissions. They were organized in topical sections as follows: Chip and Accelerators, Memory and Storage, Cloud and Networking, Design for LLM and ML/AI, Big Data and Graph Processing, and Secure and Dependable System.