Several recent events raised the attention toward possible major accidents triggered by external acts of interference in industrial facilities. In particular, a growing concern is present with respect to the intentional release of dangerous substances resulting in environmental and eco-terroristic attacks. Therefore, optimal selection and allocation of preventive security measures is becoming more important for decision-makers. Despite the existence of economic models supporting the decision-making process, their applications within the chemical industry Security context are relatively limited. This study describes a specific model for economic analysis and selection of physical security measures, with respect to potential environmental and eco-terroristic attacks in chemical facilities. An example of application to a relevant case study is presented to show the model capabilities. Site-specific analysis of the baseline physical security system performance allows comparing the costs of different security upgrades with the benefits related to either prospective or retrospective losses, meanwhile accounting the uncertainties related to the threat probability. Selection of the most profitable security measures within budget constraints and definition of economic indicators are the main outputs of the model, in order to support decision-making processes for allocation of security barriers. (C) 2017 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.