Twitter, Microblogging service has hired Dick Costolo, a former Google Inc. executive to be its chief operating officer, in a move that will assist the fast-growing company to complete its management team.

Dick Costolo who is also an investor in Twitter, will shoulder his new responsibility from next week.

Twitter that has a workforce of around 60 people lets its users to publicize text messages of up to 140 characters over the Internet to groups of followers.

Data compiled by the comScore showed that the number of unique visitors to the Twitter website touched 44.5-million point in June.

Biz Stone, co-Founder of Twitter, had said in May that the company was looking for ways to coin money from its free service.

Dick Costolo had formerly worked as the Chief Executive of Feedburner, which was purchased in 2007 by Google. Then he remained at Google as a group product manager until June 2009.