In this paper, the authors investigate how Twitter is used for political communication during election periods with a specific focus on characteristics and communication behavior of influential accounts. Our analysis focuses on the state parliament election in Berlin (Germany) on 18 September 2011. Tweets of the top-30 most retweeted users are analyzed with respect to content-related features such as emotionality, appraisal of political parties or politicians, and topics. Furthermore, the authors test hypotheses regarding the relationship between sentiment in terms of emotionality and appraisals occurring in tweets and their quantity and speed of dissemination. Our work helps both researchers and politicians to better understand the nature of influentials in political communication and the role of sentiment in information diffusion on Twitter.has changed the physics of information diffusion which is no longer controlled by a small number of 'gatekeepers'. Given their tremendous growth, social media are recently increasingly used in a political context. It has been observed that in a very short time, politicians in modern democracies across the world have eagerly adopted social-media platforms seeing powerful new media in them which can be used for engaging their constituents, especially during election campaigns (Hong & Nadler 2011;Thimm et al. 2012). In this regard, US politicians are said to have a leading role with the most prominent example of Barack Obama who has successfully employed social media within the election campaigns both in 2008 and 2012. Furthermore, Twitter has become a legitimate and frequently used communication channel in the political arena for citizens (Tumasjan et al. 2011). With the unique feature of 'retweeting' as a simple yet powerful mechanism for information diffusion, Twitter is an ideal platform for any user to spread political information and opinions. Nevertheless, so-called political 'influentials' or opinion-makers exist who are said to have an impact on the political opinionmaking and agenda-setting processes as well as on communication behavior of other users. However, little research has been devoted to this group of influential users. Therefore, in this paper we seek to investigate how Twitter is used for political communication during election periods with specific focus on characteristics and communication behavior of influential accounts.Given the rapid growth of social media, people are enabled to express their opinions, appraisals, attitudes, and emotions -which are generally termed as sentiment (Pang & Lee 2008; Liu 2011) -more than ever on almost anything in forums, weblogs, social networks, and reviews. This applies particularly to political communication which is assumed to be of polarizing controversial nature. Yet it is unclear how sentiment might impact the dynamics of information in a social-media setting. Therefore, as another contribution, we aim at examining whether sentiment of political tweets -both in terms of emotionality and appraisal -have an influence...