The paper reports on a small pilot study that explores the role of mobile technology (m-technology) in English as second language (ESL) vocabulary learning for working adult learners. In this study, through the use of Short Message Service (SMS), mtechnology was integrated into web-based vocabulary learning for working adult learners. This pilot study examined learner experiences of m-technology used in the workplace in Hong Kong. Ten learners were involved in the study. Both quantitative and qualitative methods were adopted through assessments using an online test system and an open-ended questionnaire sent by email to collect data. The research findings show significant improvements in the learner performance and in their attitudes towards using mtechnology in their learning.