La0.8Sr0.2Ga0.8Mg0.2O3 (LSGM) is considered a promising electrolyte for intermediate-temperature solid oxide fuel cells (IT-SOFCs) due to its high ionic conductivity and stability under fuel cell operating conditions. Here we report our findings in investigating the feasibility of using a high velocity oxygen fuel flame (HVOF) spraying process for cost-effective fabrication of dense LSGM electrolyte membranes. The flame and in-flight particle behavior were simulated numerically to optimize the microstructure and phase compositions of the LSGM deposits. The measured gas leakage rate of an LSGM deposit is ∼7 × 10−7 cm4gf−1 s−1. The single cell assembled with 50–55 μm HVOF-sprayed LSGM electrolyte shows open circuit voltage (OCV) of 1.08 V at 800 °C, suggesting that the as-sprayed LSGM deposit is dense enough for direct application as SOFC electrolyte. At 800 °C, the ionic conductivity of the sprayed LSGM deposit is ∼0.04 S cm−1, indicating that the HVOF spraying is a promising process for low-temperature fabrication of dense LSGM electrolyte membranes for IT-SOFCs.