A novel radiation dosimetry method using lactose was investigated through electrical conductivity measurements. 2–12 wt% % lactose solutions were gamma-irradiated using 60Co, with 2 wt% showing optimal sensitivity. Electrical conductivity showed superior linearity (1–210 kGy) compared to optical absorption (1–17.5 kGy). At medium and high doses, the dose–response in electrical conductivity had better sensitivity than optical absorption (0.473 vs 0.147) and (0.252 vs 0.162). The temperature significantly affected the measurement of electrical conductivity (166.4% increase at 65 °C) and optical absorption (100.8% increase at 65 °C), while daylight had a negligible effect. © Akadémiai Kiadó Zrt 2025.