Tranquil spaces are under threat throughout the world from transportation noise and industrial sound especially in densely populated areas. They are vitally important to health and wellbeing and the relief of stress from sustained attention necessary in urban living. For this reason, tranquility spaces are often referred to as “restorative environments”. Therefore, it is important to elucidate, identify, protect and if possible enhance the benefits of these areas. A tool is required to facilitate these key tasks. The study conceptualized the understanding of tranquility and deciphered whether or not some places are considered tranquil in Hong Kong; and what their characteristics are and how people perceive such places. As tranquility is often associated with noise, the method involved the assessment of traffic noise and the measured the percentage of natural and contextual features at the scenes. Validation and subsequent analysis involved the adoption of Tranquility Rating Prediction Tool (TRAPT) that was tested in the UK. This unique tool is useful in identifying valued tranquil spaces and can be used by a range of stakeholders including administrators, planners and those charged with park and countryside management. The research evaluated the usefulness of tranquil spaces in the Hong Kong situation by first validating and calibrating its predictions using local residents. The tranquility assessments in this were compared with those used to develop the prediction tool and thus enabled the tool to be validated so as to suite the local situation. Its applicability was demonstrated in six contrasting environments in urban and rural parks and open spaces. For this purpose, the range of tranquility in the selected areas was predicted. In addition to this, a questionnaire survey of users of these selected areas were used to further evaluate perceived tranquility, benefits and reasons for any enhanced ratings or shortfalls. The results and analysis generated, add to the growing body of knowledge in this discipline and could help decision makers, planners and those with responsibility for the management of open spaces and countryside environment. This consequently helps to relate perceived tranquility to the degree of relaxation reported by questionnaire respondents and in addition their personal levels of anxiety. This link is important in establishing the tool as a measure of the restorative nature of an environment which relates directly to important issues of health and well being