This thesis focuses on the planning of material quantities in an aircraft maintenance organization (MRO). Parts and materials are classified according to EU Regulation 1321/2014, which prescribes uniform safety standards for all MRO organizations within the European Union. The objective of the study is to determine the optimal inventory levels of materials and parts necessary for the seamless operation of a Ni-Cd battery maintenance workshop, storage methods, and conditions required to maintain material quality. The research problem addresses the challenges faced by MRO organizations in planning the required materials. Materials and parts are categorized into standard parts, raw and consumable materials, and components, which include rotating, repairable, and non-repairable parts. Proper storage of these materials demands significant resources to ensure quality and operational continuity. The ABC analysis was applied to determine the required quantities of materials and parts for the maintenance of Ni-Cd batteries. The study examines which materials are essential for storage, how they should be stored, and under what conditions. Key challenges include limited storage space and the availability and procurement of materials. The methodology consists of theoretical and practical components. The theoretical part employs methods such as analysis, synthesis, description, compilation, and induction. The practical part is based on performing an ABC analysis using available data from aviation operators. The material flow from suppliers to storage and eventual installation on aircraft is analyzed. The research hypotheses are: 1. The value of materials and parts in storage is a critical factor for applying the ABC method. 2. The ABC method is suitable for optimizing inventory management in MRO organizations.