This study explores the use of speech acts in Computer Mediated Communication (CMC), particularly on Social Networks Sites (SNS). The present study expands on previous studies by Dauterman, Schrock and Carr (2012), and examines speech acts by President Donald Trump on Twitter. The study explored a period of four months of Trump's tweets, two months before the election and two months after him becoming a president. In the first period from the 8th of September, 2016 till the 8th of January 2017, president Trump created 709 tweets including 1253 speech acts components. Content analysis of such data shows that his tweets were most frequently constructed with assertive speech acts, followed by expressive ones. In the second period from the 20th of January till th 20th of March 2017, president Trump created 283 tweets containing 348 speech acts components. In the second duration the expressive speech acts type was the most dominant one followed by the assertive type. The total results of the two durations showed the production of 992 tweets that contained 1601 components of speech acts. In addition, the most frequently used speech act type was assertive followed by expressive. The usage of these types of speech acts might reflect the need of Donald Trump as presidential nominee to act seriously in the studied periods.