This open access book constitutes the proceedings of the 30th International Conference on Automated Deduction, CADE 30, which took place in Stuttgart, Germany, during July 2025.CADE is the major forum for the presentation of research in all aspects of automated deduction, including foundations, applications, implementations, and practical experience.The 33 full papers and 4 short papers included in these proceedings were carefully reviewed and selected from 87 submissions. ...