This study examines the motivation of 20 Japanese students of English as a foreign language (EFL) who chatted electronically with 19 Taiwanese EFL students using online synchronous chat software. In particular, we were interested in four factors that affect task-based motivation: the willingness to communicate, task attractiveness, task innovativeness, and the need to communicate in the target language. Qualitative analysis of a posttest questionnaire and the texts that students produced during their online task reveal that students were generally motivated throughout the task with respect to all four of the factors. It is suggested that well-designed online chat tasks, whereby students need to arrive at a consensus via interaction, can be very motivating to students. For teachers, electronic synchronous chat represents one more valuable tool for language teachers to facilitate interaction in the target language. (Contains 5 figures and 2 tables.)