The objective was to evaluate the effect of biological silage inoculant with and without hydrolytic enzymes on temperature profile of alfalfa fermentation at 20oC and 30oC compared to control and formic acid. A 4×2 factorial experiment was designed with continuous temperature monitoring for 51 days using DS1922L sensors. All tested additives showed statistically significant differences compared to control (p < 0.05), except formic acid at 30oC. The largest effect was recorded for enzyme inoculant at 30oC (+0.76oC). Dry matter fermentation losses ranged from 0.54% (formic acid, 30oC) to 3.42% (control, 20oC). Enzyme inoculant achieved highest lactic acid to volatile fatty acids ratio at 30oC (3.46) and 20oC (3.01). Continuous temperature monitoring proved suitable for evaluating silage additive effectiveness.