Inappropriate antibiotic use is a major cause of antibiotic resistance. Therefore, optimizing antibiotic usage is essential. In Belgium, optimization of antimicrobials for the fight against multidrug resistant organisms (MDROs) is followed up by national surveillance by public health authorities. To improve appropriate antimicrobial use in hospitals, an effective national Antimicrobial Stewardship (AMS) program should include indicators for measuring both the quantity and quality of antibiotic use. The aim of this study was to develop a set of process quality indicators (QIs) to evaluate and improve AMS in hospitals. A RAND-modified Delphi procedure was used. The procedure consisted of a structured narrative literature review to select the QIs, followed by two online questionnaires and an intermediate multidisciplinary panel discussion with experts in infectious diseases from general and teaching hospitals in Belgium. A total of 38 QIs were selected after the RAND-modified Delphi procedure, from which 11 QIs were selected unanimously. These QIs address compliancy of antibiotic therapy and prophylaxis with local guidelines, documentation of the rationale for antibiotic treatment in the medical record, the availability of AMS Programs and Outpatient Parenteral Antibiotic Therapy, resistance patterns and antimicrobial prescribing during focused ward rounds. Our study selected 38 relevant process QIs, from which 11 were unanimously selected. The QIs can contribute to the improvement of quality of antibiotic use by stimulating hospitals to present better outcomes and by providing a focus on how to intervene and to improve prescribing of antimicrobials.