Purpose: The main aim of this paper is to analyze the relationships between the corporate motivations that lead organizations to establish the ISO 50001 Energy Management System (EnMS) standard, and the difficulties and benefits derived from its adoption. Design/methodology/approach: Three independent exploratory factor analyses (EFA) were conducted in order to identify (i) sources of motivation: social requirements, ecology drivers, and competitive advantage; (ii) the difficulties of an ISO 50001 adoption: operational difficulties and organizational difficulty; and (iii) types of benefits: ecological benefits and operational benefits. In a second step, an exploratory path analysis, performed through Structural Equation Modeling (SEM), was used to analyze the relations among motivation, difficulties, and benefits related to the adoption of the ISO 50001 standard. Findings: Social requirements explain operational difficulties, which in turn impacts on operational benefits. Ecology drivers are directly related to ecological benefits. Organizational difficulties have an inverse relationship with operational and ecological benefits. Operational difficulties are related to operational benefits and ecological benefits. Research limitations/implications: The questionnaire was disseminated to 87 Spanish companies with ISO 50001 certification. Managers and other practitioners such as consultants, auditing companies, and official organizations in charge of developing standards might find useful implications. Originality/value: The standard was published in 2011 by the International Organization for Standardization (ISO). This paper contributes to assessment of the benefits of the standard by collecting information directly from the pioneer organizations that have adopted it, and provides clues on how to implement the standard and improve it in future.