Yuenyong S.Viriyayudhakorn K.Piyatumrong A.Jaroenkantasima J.Mahidol University2026-02-062026-02-062026-01-01Lecture Notes in Computer Science Vol.15837 LNCS (2026) , 210-21903029743https://repository.li.mahidol.ac.th/handle/123456789/114548OpenThaiGPT 1.5 is an advanced Thai language chat model based on Qwen v2.5, finetuned on over 2,000,000 Thai instruction pairs. This report provides an engineering perspective on the model’s development, capabilities, and performance. We discuss the model’s architecture, training process, and key features, including multi-turn conversation support, Retrieval Augmented Generation (RAG) compatibility, and tool-calling functionality. Benchmark results demonstrate OpenThaiGPT 1.5’s state-of-the-art performance on various Thai language tasks, outperforming other open-source Thai language models. We also address practical considerations such as GPU memory requirements and deployment strategies.MathematicsComputer ScienceConference PaperSCOPUS10.1007/978-3-031-97144-0_192-s2.0-10501109776916113349