Human capital investment is a necessary condition for improving labour market outcomes in most countries. Empirical studies to investigate human capital and its linkages on the labour demand side are, however, relatively scarce due to limitations of firm-level data-sets. Using firm-level data from the Thai manufacturing sector, this paper aims to investigate the effects of skill and human capital on labour productivity. Costs and benefits of human capital improvement are compared indicating that hiring workers who have higher education as well as providing them with in-service training has a statistically and significantly positive impact on an increase in labour productivity. However, hiring workers who have higher education yields less benefit than costs which come from higher average wage expenditures. However, providing training should contribute more benefit than cost. Besides education and training measures, we also measure workers' skill levels into cognitive skills and non-cognitive skills and find that skill in information technology is found to be the most important cognitive skill for increasing labour productivity among Thai manufacturers. Non-cognitive skills such as those in leadership, time-management and communication are also important and seem to have positive relationship to labour productivity among Thai manufacturers.