A bibliometric analysis was conducted on social media research in journals under the subject category “Information Science & Library Science” of the Social Science Citation Index. 646 articles were retrieved using the term “social media” as a keyword to search parts of titles, abstracts or keywords of publications. The research performance and trends were analyzed with descriptors of types and languages, characteristics, countries, journals, authorships and author keywords. Results showed that, social media research steadily increased from the period of 2002 to 2013 and the annual publication output in 2012 and 2013 were almost half of the total. A total of 9,851 pages, 29,433 cited references, 1,540 authors and 3,740 citations were identified in all 646 articles, with the average per article of 15.25 pages, 45.46 cited references, 2.38 authors and 5.79 citations. Analysis of countries and journals suggested an uneven distribution of publications on national and journal levels. The USA attained a leading position by contributing the largest share of articles. UK, Spain and China were the other three top productive countries in total publications. 73.53% of the total articles were published in 25 journals with impact factors ranging from 0 to 5. More than half (51.24%) journals had an impact factor between 1 and 3. Journal of Health Communication with 2.079 IF had published the most articles. The most commonly used author keywords appeared in the articles were “social media”, “social network”, “Internet”, “communication”, “Web 2.0”, “blog”, “Twitter”, “Facebook” and “virtual community”.