Solid Oxide Cells (SOCs) including solid oxide fuel cells (SOFCs) and solid oxide electrolysis cells (SOECs) hold great potential for commercial viability due to their high heat utilization, reduced carbon emissions, high efficiency and fuel flexibility. A key component in enhancing cell performance and extending lifetime is the thin and dense ceria-based barrier layer at the electrolyte and air electrode interface to avoid cell degradation during manufacturing, the barrier layer needs to be densified at low temperatures (ideally less than 1000 ℃), which remains a significant challenge currently. This review focuses on the typical low-cost ceramic powder-based route for the preparation of the barrier layer exploring various approaches to achieve low-temperature densification. It covers techniques such as synthesizing finer powders, optimizing deposition methods for the green-body layer, using sintering aids, and employing post-sintering processes to enhance density. Recent advancements in these areas are highlighted to provide insights into future development directions. Finally, the review discusses new opportunities and emerging techniques that could further improve the barrier layer performance.