This study explores the role of ChatGPT as a Computer-Assisted Language Learning (CALL) tool in English language education, focusing on the adoption of ChatGPT through the Hedonic Motivation System Adoption Model (HMSAM). Using structural equation modelling (SEM), the research analyzed data from 189 responses collected via an online survey of Chinese international students in UK universities. The findings reveal that ChatGPT's adoption is influenced by factors such as perceived ease of use, perceived usefulness, control, joy, and focused immersion. These factors significantly mediate the relationship between perceived ease of use and behavioral intention. The study confirms that perceived usefulness of ChatGPT significantly enhances users' control, curiosity, and joy, while reducing boredom. Focused immersion is significantly predicted by control, boredom, perceived usefulness, and joy. Behavioral intention to use ChatGPT is significantly influenced by boredom, perceived usefulness, and focused immersion. The research model demonstrates a good fit with the data, indicating that the proposed relationships among variables reasonably represent the empirical data. The study contributes to understanding the factors influencing the adoption of AI tools in language education and provides insights for future research and practice in English language teaching and learning.This study explores the role of ChatGPT as a Computer-Assisted Language Learning (CALL) tool in English language education, focusing on the adoption of ChatGPT through the Hedonic Motivation System Adoption Model (HMSAM). Using structural equation modelling (SEM), the research analyzed data from 189 responses collected via an online survey of Chinese international students in UK universities. The findings reveal that ChatGPT's adoption is influenced by factors such as perceived ease of use, perceived usefulness, control, joy, and focused immersion. These factors significantly mediate the relationship between perceived ease of use and behavioral intention. The study confirms that perceived usefulness of ChatGPT significantly enhances users' control, curiosity, and joy, while reducing boredom. Focused immersion is significantly predicted by control, boredom, perceived usefulness, and joy. Behavioral intention to use ChatGPT is significantly influenced by boredom, perceived usefulness, and focused immersion. The research model demonstrates a good fit with the data, indicating that the proposed relationships among variables reasonably represent the empirical data. The study contributes to understanding the factors influencing the adoption of AI tools in language education and provides insights for future research and practice in English language teaching and learning.