Individuals born between the 1980s and the early 2000s, also known as millennials, were the largest age group of online shoppers in Thailand in 2016, according to a survey.
As of December, the number of online shoppers totalled 17 million out of the 40 million internet users in the country.
The survey was conducted last October by Manhattan Associates, a US-based developer of supply chain software, with 2,000 respondents in Bangkok and smaller cities.
"About 40% of online shoppers in Thailand were millennials, and this age group was the most frequent shoppers as 44% responded they shop online two to three times per month," said Richard Wright, managing director of Manhattan Associates in Southeast Asia.
Mr Wright said Thailand's e-commerce market will continue to grow, with clothes and fashion, high-tech and electronic products, and cosmetics the three best-selling products online.
The survey found inaccurate and slow delivery is the greatest frustration for Thai online shoppers aged between 35-54 years.
Another frustration is not being able to return goods easily, with 45% of respondents saying they experienced difficulty in returning or exchanging products.
Some 88% of respondents want same-day delivery services.
Respondents ranked faster and more convenient fulfilment in addition to more frequent promotions the most important factors that would encourage them to do more online shopping.
Some 77% of respondents indicated reliable delivery makes them a more loyal customer.
Mr Wright also said competition in Thailand's e-commerce market will become more intense because of the entry of Chinese e-commerce giant Alibaba, forcing major local retailers and e-commerce operators to transform their organisations to improve their operational efficiency, especially for warehouse and distribution management systems.
The warehouse management software market in Southeast Asia, including Thailand, is expected to continue to record strong growth this year after registering a rapid uptick in the country last year.