Response time has always been a concern in ability measurement, sometimes implicitly as in time-limit tests, sometimes explicitly as in speeded tests, and sometimes as the main outcome variable. Therefore, this study seeks to investigate the application of response time model in measuring cognitive ability of the children's quantitative reasoning. To this end, a sample of 502 children from different areas of Tehran was recruited through Cluster sampling and evaluated with a quantitative reasoning test. To analyze the collected data, modeling response time with the hierarchical model was used. Item and person parameters were also estimated and interpreted. The modeling results revealed that in addition to the response correctness parameters, response time parameters including discrimination coefficient, difficulty coefficient and gamma also been estimated. Moreover, the estimated parameters of the response time model compared with the 2-pl IRT model in order to identify their main similarities and differences. Findings revealed that there are some differences in discrimination coefficients and Thetas of individuals, which indicates the power of the response time model. It is worth mentioning that the lowest differences were observed in the difficulty coefficients. Finally, based on the number of parameters, increasing the variance of theta scores, and research background support, the study and application of response time models in measuring children's cognitive abilities were suggested.