The study investigated the influence of white vs 12 background and overlay colours on the reading process in school age children. Previous research reported that colours could affect reading skills as an important factor of the emotional and physiological state of the body. The aim of the study was to assess developmental differences between second and third grade students of elementary school and to evaluate differences in electroencephalography (EEG), ocular, electrodermal activities (EDA) and heart rate variability (HRV). Our findings showed a decreasing trend with age regarding EEG power bands (Alpha, Beta, Delta, Theta) and lower scores of reading duration and eye-tracking measures in younger children compared to older children. As shown in the results, HRV parameters showed higher scores in 12 background and overlay colours among second than third grade students which is linearly correlated to the level of stress and readable from EDA measures as well. The existing study showed the calming effect on second graders in turquoise and blue background colours. Considering other colours separately for each parameter, we assumed that there are no systematic differences in Reading duration, EEG power band, Eye-tracking and EDA measures.