Older adults (OA) increasingly use smartphones, which provide visual, auditory, and haptic signals. However, it remains unclear if multimodality's positive effects on performance during controlled experiments and driving scenarios apply to OA smartphone interaction. Multilevel models showed that reaction times (RT) of 18 younger adults (YA) and 15 OA to unimodal stimuli $(\mathbf{M}=1,178\ \mathbf{ms})$ are significantly higher $[\mathbf{F}(2,5_{9}308.7)=69.17, \mathbf{p} <. 001]$ than to bimodal $(\mathbf{M}=1,110\ \mathbf{ms};\ \mathbf{do}\ =0.26)$ or trimodal stimuli $(\mathbf{M}$ = 1,071; $\mathbf{do} =0.42)$. The difference between unimodal $(\mathbf{M}=1,307)$ and bimodal stimuli $(\mathbf{M}=1,216;\ \mathbf{do}\ =0.35)$ and between unimodal and trimodal stimuli $(\mathbf{M}=1,188: \mathbf{do} =0.46]$ ), was greater for OY than YA $[\mathbf{F}(2,5_{2}308.7)=3.77;\mathbf{p}=.023]$. Results thus confirm findings from aging and multimodal information processing literature and suggest using more than one feedback modality to improve OAs smartphone interaction.