Safer, highly effective biocides providing long-term protection of mold growth on wood-based materials is of interest to the wood protection industry. Moldicide formulations containing synergistic combinations of ingredients derived from natural sources are commonly recognized as a promising approach for the next generation of wood protectants. Although fatty acid (FA)–based chemistry has had some development in food sanitation and agriculture, little exploration relating to new mold inhibitors for wood and wood products has occurred. Low molecular weight, saturated monocarboxylic acids combined with selected adjuvants can effectively inhibit mold spore germination. Specifically, formulations containing valeric or pentanoic (C5), hexanoic or caproic (C6), heptanoic (C7), caprylic or octanoic (C8), pelargonic or nonanoic (C9), and/or decanoic or capric (C10) saturated acid demonstrated efficacy against mold growth for up to 12 weeks in the ASTM D4445 standard laboratory test for mold. Pressure-treated wood was more resistant to mold growth than wood dip treated with FA formulations.