Water atomization (WA) of a molten metal is a well-established and cost-effective industrial approach to producing low-reactive metal powders. However, WA powders are characterized by a wide spread of particle size unsuitable for certain powder metallurgy applications. To address this limitation, this thesis examines some of the poorly understood fluid mechanics phenomena involved in WA, to develop fundamental knowledge that describes the relationships between the design and operating conditions of a water atomizer, and the particle size distribution (PSD) of the resulting powder.