E-commerce sales increased 12% in November compared with the same month a year ago, MasterCard reported today in its SpendingPulse report. November brought the first double-digit growth for e-commerce sales since July, and the largest increase for the category since May, according to MasterCard’s estimates.

Online apparel sales did especially well last month, increasing 22.2%. Apparel posted the twelfth consecutive month of double-digit growth online, according to MasterCard Advisers, a consulting arm of the payment card network. Total apparel sales, which includes transactions in bricks-and-mortar stores, increased 9.6%, the largest year-over-year growth rate in 2010. E-commerce sales of children’s clothes increased 33.3%, while online sales of shoes jumped 32.7%, the first time since March that web spending on footwear increased more than 20%.

Women’s online apparel sales registered a more modest growth rate, 7%.

The SpendingPulse report is based on retail sales using all payment forms, including credit and debit cards of all brands, cash and checks. The report did not offer a general figure for overall retail growth, which MasterCard provides only on a quarterly basis. But in another report released today, Kantar Retail, a consulting firm, reported that retail same-store sales increased 6% in November compared with the same month last year. The figures take into account sales data from 30 retailers, most of them selling apparel.

MasterCard attributed some of the e-commerce growth last month to holiday efforts from retailers. “There were some early season promotions before Thanksgiving,” says Michael McNamara, vice president, research and analysis for MasterCard Advisors. “Free shipping and those sorts of things drive traffic online.” He adds that retailers often offered Black Friday sales online that matched discounts in bricks-and-mortar stores, further encouraging e-commerce holiday shopping. Black Friday is the day after Thanksgiving.

Online spending for consumer electronics increased 6% in November, with sales especially strong during Thanksgiving week, MasterCard says. Consumer electronics sales were up only 1% when bricks-and-mortar stores are included. E-commerce sales for department stores—this category excludes warehouse and discount chains—increased 5.6% in November. The category had negative growth when including sales from bricks-and-mortar locations, McNamara says.