<p class="heading1" style="mso-list: none; tab-stops: 36.0pt;"><span lang="EN-US" style="font-weight: normal;">This book CCIS 2486 constitutes the refereed proceedings of the 9th International Conference on Modelling and Development of Intelligent Systems, MDIS 2024, held in Sibiu, Romania, during October 17–19, 2024. </span></p><p class="heading1" style="mso-list: none; tab-stops: 36.0pt;"><span lang="EN-US" style="font-weight: normal;">The 16 full papers were carefully reviewed and selected from 42 submissions. The MDIS 2024 focuses on </span></p><p class="heading1" style="mso-list: none; tab-stops: 36.0pt;"><span lang="EN-US" style="font-weight: normal;">Machine Learning,</span></p><p class="heading1" style="mso-list: none; tab-stops: 36.0pt;"><span lang="EN-US" style="font-weight: normal;">Intelligent Systems for Decision supports,</span></p><p class="heading1" style="mso-list: none; tab-stops: 36.0pt;"><span lang="EN-US" style="font-weight: normal;">Modelling and optimization of Dynamic Systems,</span></p><p class="heading1" style="mso-list: none; tab-stops: 36.0pt;"><span lang="EN-US" style="font-weight: normal;">Evolutionary Computing and Metaheuristics,</span></p><p class="heading1" style="mso-list: none; tab-stops: 36.0pt;"><span lang="EN-US" style="font-weight: normal;">Security and Cryptography in Dynamic Systems.</span></p>