To fill the gaps in the computer mediated communication literature and provide useful information on interpersonal relationships within an organization, this study aims to investigate how computer mediated communication (CMC) system have impacted on employee's job satisfaction of Ceylon Electricity Board, Sri Lanka. An empirical research was conducted to test the hypothesized relationships based on a conceptual framework developed through a comprehensive literature review on CMC and job satisfaction. Through a literature support this model consisted of three independent variables (i.e., electronic mails, instant messaging and computerized maintenance management) in computer mediated communication system and a dependent variable which is job satisfaction. The sample of the study consisted of 100 respondents representing executive and medium level technical service (MLTS) staff of the transmission division of Ceylon Electricity Board in Sri Lanka. Self-administered questionnaire and the web-based questionnaire was used to collect primary data. The data were analyzed with Partial Least Squares path modeling (PLS) to test the hypotheses of the study. The research findings indicated that computerized maintenance management is the most significant factor impacting on the employees' job satisfaction. Moreover, it also identified that there is a positive and statistically significant impact of instant messaging and electronic mails on employees' job satisfaction. The results provide valuable input regarding the instant messaging and job satisfaction. Therefore, managers should have to pay their more and more attention in order to improve instant messaging as one of the communication media in an organization. In this research considered only three CMC dimensions which influence the job satisfaction. But there are more CMC dimensions used as organizational communication in future studies.