Two acidic soils (initial pH, 4.6) with contrasting soil organic C (SOC) contents (11.5 and 40Â gÂ CÂ kgâ»Â¹) were incubated with Â¹Â³C-labelled lime (CaÂ¹Â³COâ) at four different rates (nil, target pH 5, 5.8 and 6.5) and three application depths (0â10, 20â30 and 0â30Â cm). We hypothesised that liming would stimulate SOC mineralisation by removing pH constraints on soil microbes and that the increase in mineralisation in limed soil would be greatest in the high-C soil and lowest when the lime was applied in the subsoil. While greater SOC mineralisation was observed during the first 3Â days, likely due to lime-induced increases in SOC solubility, this effect was transient. In contrast, SOC mineralisation was lower in limed than in non-limed soils over the 87-day study, although only significant in the Tenosol (70Â Î¼gÂ CÂ gâ»Â¹ soil, 9.15%). We propose that the decrease in SOC mineralisation following liming in the low-C soil was due to increased microbial C-use efficiency, as soil microbial communities used less energy maintaining intracellular pH or community composition changed. A greater reduction in SOC mineralisation in the Tenosol for low rates of lime (0.3 and 0.5Â gÂ columnâ»Â¹) or when the high lime rate (0.8Â gÂ columnâ»Â¹) was mixed through the entire soil column without changes in microbial biomass C (MBC) could indicate a more pronounced stabilising effect of CaÂ²âº in the Tenosol than the Chromosol with higher clay content and pH buffer capacity. Our study suggests that liming to ameliorate soil acidity constraints on crop productivity may also help to reduce soil C mineralisation in some soils.