Current evaporation methods adopted in South America to extract lithium from brine are not suitable for Canadian brine sources in British Columbia, Alberta, and Saskatchewan. Not only is the process inefficient with significant losses, but cold climate conditions would require new processes or technologies. Much of the research and development focus is on adsorbent technologies with limited investigation on direct lithium extraction using solvent extraction due to poor efficiency when using conventional mixer-settlers as well as poor separation between monovalent and divalent cations with existing extractants. At the National Research Council Canada (NRCC), studies to identify new extractants to improve separation and the development of supported liquid membranes (SLM) to increase efficiency when processing brines are being undertaken. This chapter demonstrates the improved separation efficiency component of SLM. Benchscale monovalent separations were performed on a synthetic brine, 4000 ppm each of Li, Na, and K, based on the Mextral 3936H data sheet as a first benchmark. Results between shakeout solvent extraction, flatsheet SLM, and hollow-fibre SLM are compared with the manufacturer’s data sheet and against each technology.