Background Children with disabilities like ADHD, Autism or Intellectual Disabilities may have problems with everyday functioning related to time management and hence there is a need to develop systematic methods for evaluation of the ability to understand and use time information. The purpose of this study was to examine aspects of construct validity of a new instrument, KaTid, for assessing time processing ability (TPA) in children. Methods Data from 144 typically developing, 5-10-years-old typically developing children, were analysed with Rasch analysis. Instruments used were the KaTid, a self-rating scale measuring autonomy in daily routines and a parent scale measuring daily time management. Results Fifty-one items in KaTid, initially defined in three subcategories: time perception, time orientation and time management, all demonstrated acceptable goodness-of-fit to a Rasch model, indicating evidence of internal scale validity. Performance of the children on the KaTid also provided evidence for validity in response processes and that it may discriminate among children with different levels of TPA. Relationships between the KaTid measures and the parents' ratings of the child's daily time management indicated further evidence of construct validity. Conclusions The results of this study supports evidence of construct validity in the KaTid when used with typically developing 5-10 years-old children. Further research is needed to evaluate the validity of KaTid in children with known time processing difficulties.