The purpose of this study was to develop and test a measuring instrument based on the Gibb’s Defensive Communication Climate Paradigm (1961) to assess the communication climate focus of professional nurses in selected public hospitals in the Gauteng province. This focus involves the communication behaviour orientation of the professional nurses and their perceptions of the communication behaviour orientation of their operational managers. The Gibb’s model comprises six bipolar conceptual continuums, namely Evaluation-Description, Control-Problem orientation, Strategy-Spontaneity, Neutrality-Empathy, Superiority-Equality and Certainty-Provisionalism Continuums. The study consisted of a non-experimental design, including a developmental phase and a testing phase. During the developmental phase the researcher developed a measuring instrument (a Semantic Differential Scale questionnaire); used a simple, random sample method to pre-test the instrument; analysed the data by applying Cronbach’s Alpha reliability analysis and refined the instrument. Further refinement of this new instrument by future researchers is recommended. During the testing phase the researcher also used a simple, random sample, consisting of professional nurses (N = 270) from three selected public hospitals in Gauteng; tested the items against the biographical data and the three research questions and analysed the obtained data by utilising both descriptive and inferential statistics. A Delphi panel of experts were involved in both phases of the study. The results of the study indicated that although the respondents had a predominantly supportive communication behaviour orientation, they were more focused on the communication behaviour of their operational managers than on their own. Furthermore, the results indicated no significant differences in the influencing factors: age, tenure (periods in hospital), gender, language and institution (public hospital), in terms of the six conceptual continuums. Significant differences were found only in the factor: unit/ward, indicating that the supportiveness of the communication behaviour of professional nurses could be dependent on their specific work environment. Guidelines aimed at the development of a supportive climate were drawn up for the National Department of Health, Gauteng Department of Health, public hospitals, operational managers and professional nurses. It is recommended that implementation of the newly developed guidelines be pivotal for public hospitals, to refocus their communication climates towards supportive communication. / Health Studies / D. Litt. et Phil. (Health Studies)