Abstract With the popularity of synchronous instant messaging software, this thesis is the first study that examines emoticons, acronyms and other literacy practices of synchronous computer-mediated communication (hereafter CMC) of youngsters in Macau. The research questions include examining the reasons, types of emoticons, and CMC literacy practices used among youngsters in Macau, as well as their impact in the style of communication in CMC. The findings are compared with a similar study in Hong Kong. There are two parts in this study — questionnaire and analysis of chat histories submitted by subjects using instant messaging software—ICQ or MSN Messenger. 170 questionnaires are distributed to university students in Macau and 16 chat histories are analyzed. Findings reveal that the types of emoticons, acronyms and literacy practices are similar to the counterpart in Hong Kong. Reasons for employing emoticons are (1) habitual, (2) contagion, 3) ease to use and 4) expressive while saving typing strokes and forming intimacy are the two reasons for employing acronyms. In addition, other literacy practices such as grammar mistakes and addition of Cantonese final particles in CMC are also discussed. Keywords: computer-mediated communication, emoticons, internet acronyms, ICQ, Macau, MSN Messenger