<p>A novel colorimetric analysis of methylcellulose (MC) hydrogel was conducted using a standard smartphone camera to measure its thermo-optical properties. As demonstrated for the first time, the temperature of MC gels was directly determined from photographs by exploiting a unique one-to-one correlation between temperature and mean pixel intensity in the blue channel of RGB images, all color channels showed strong hysteresis. Two innovative procedures for gelation assessment are introduced: variance analysis and histogram analysis with normal distribution fitting. The variance analysis confirms known gelation related temperatures, validating the effectiveness of the new method. Histogram analysis reveals a significant increase in RMSE (root mean square error) near gelation related points, offering a new indicator for gelation status. This methodology underscores the untapped potential of colorimetry to extract valuable data from hydrogels in general and MC gel in particular.</p>