Background: This study examined the validity and reliability of two smartphone-based tasks, the Symbol Search Task (SST-SP) and the Dot Memory Task (DMT-SP), in cognitively healthy older adults. Methods: Sixty participants (32 older and 28 younger adults) completed two sessions approximately one week apart. In the first session, participants performed standardized cognitive tests (Symbol Digit Substitution Test and Visual Digit Span Test) on a personal computer (PC), PCbased Symbol Search Task (SST-PC), and Dot Memory Task (DMT-PC), followed by the SST-SP and DMT-SP. The second session included only SST-SP and DMT-SP. Results: In older adults, the correlation between the SST-SP and SST-PC was very strong (r=0.83). In addition, the SST-SP showed a moderate correlation with the Symbol Digit Substitution Test (r=0.50). A very strong correlation was observed between DMT-SP and DMT-PC (r=0.86). The DMT-SP also showed a moderate correlation with the Visual Digit Span Test (r=-0.47). The SST-SP demonstrated good test–retest reliability and high split-half reliability, whereas the DMT-SP showed moderate test– retest reliability and acceptable-to-good split-half reliability. Older adults scored lower than younger adults on both the SST-SP and DMT-SP. Conclusion The SST-SP and DMT-SP are valid and reliable tools for assessing processing speed and working memory, respectively, in cognitively healthy older adults. These tools may provide new strategies for assessing the cognitive performance and/or ability in older adults in both research and clinical settings.