The number of Americans who accessed financial accounts (bank, credit card, or brokerage) via mobile devices reached 29.8 million at the end of 2010, a 54 percent increase over 2009, according to a new report from comScore.

“More people are turning to the convenience of mobile devices for their financial service needs, fueled in part by the adoption of smartphones, 3G devices and unlimited data plans,” said Sarah Lenart, comScore vice president.

“The ubiquitous nature of mobile devices affords financial brands an important channel to reach and engage customers, whether it’s at home, work or on-the-go. As brands compete for customer loyalty in this competitive market, marketers will need to focus on continually improving the mobile customer experience and adjusting to the changing landscape and consumer needs as they access their financial information.”

Mobile browsers were accessed by 18.6 million users to view financial information in the fourth quarter of 2010 , up 58 percent from the previous year, 10.8 million accessed their accounts via applications, up 120 percent. SMS (text message) represented the smallest access point for financial service audiences with 8.1 million users, up 35 percent.

Among mobile banking and credit card users, nearly half prefer going online via a fixed device as the main way to access their accounts, with 47 percent of mobile banking customers and 44 percent of mobile credit card users doing so. Mobile has become an increasingly important access channel with 36 percent of mobile credit card users and 26 percent of mobile banking customers indicating it is their primary method of accessing their accounts. Only a small segment of these users listed speaking with a representative in person or on the phone as their preferred access method.

comScore also looked at the reasons people do not use mobile devices for financial activities. The results indicated that preference for using a fixed online device topped the list for both smartphone and non-smartphone users at 53 percent and 45 percent, respectively. Security concerns were also rated highly as a concern among both smartphone users (33 percent) and non-smartphone users (30 percent). Nearly a third (29%) percent of non-smartphone users said cost was a reson for not accessing accounts, while only 10 percent of smartphone users said the same thing (as unlimited data plans void this concern for many smartphone users).

More than a quarter (26%) of smartphone users also said that slow connections speeds limited their mobile financail service usage. Only 6 percent of smartphone users and 5 percent of non-smartphone users said not knowing about these services was the reason why they did not access these accounts.