Background: Patient experience has become a key component of healthcare quality assessment and improvement. Although its importance is increasingly recognized, there is a lack of standardized instruments specifically designed to assess patient experience in relation to nursing care during hospitalization. The starting point for this study is the ELIGES-Patient Experience questionnaire developed in 2024. This study aims to refine its content by incorporating the patient perspective and to evaluate its psychometric properties through a multicenter study. The final questionnaire will be intended to assess patient experience in relation to nursing care in inpatient units, providing a reliable tool for identifying opportunities for improvement and supporting person-centered care. Methods: A three-phase multicenter mixed-methods study will be conducted. First, a focus groups with expert patients will identify the key dimensions of patient experience related to nursing care during hospitalization. The initial questionnaire will then be reviewed and revised, yielding a first provisional version. Second, a national Delphi study involving expert patients will establish consensus on the questionnaire content, thereby yielding a consensus-based provisional version of the original instrument. Third, this provisional version of the questionnaire will undergo multicenter psychometric validation in six Spanish public hospitals. A pilot study will assess temporal stability and agreement, followed by administration of the provisional version to 2271 hospitalized patients to evaluate its psychometric properties. Expected Results: Following content refinement and psychometric validation, the resulting instrument is expected to provide a standardized measure of hospitalized patients’ experience of nursing care that may help identify areas for future evaluation and quality-improvement initiatives. Conclusions: Patient experience measurement lacks standardization, which hinders comparability and limits its use as a quality improvement tool. This highlights the need for instruments that are conceptually sound, methodologically robust, and operationally applicable. A distinctive feature of this protocol is the active involvement of patients throughout the entire process, in keeping with the principles of person-centered care and helping to strengthen the relationship between healthcare professionals and patients.