Research on iconicity or sound symbolism chronicles associations between aspects of word meaning and word form. In valence sound symbolism, specifically, vowels were demonstrated to be associated with valence, so that the vowel /i/ (as in English sea) is judged to fit positively valenced stimuli, whereas the vowel /o/ (as in German Boot) is judged to fit negatively valenced stimuli. However, because previous findings were based on judgments or name invention tasks, they may reflect deliberate strategies. The present research aims to demonstrate the automaticity of valence sound symbolism in online language processing by means of a speeded response task. A total of 163 participants performed a speeded categorization task in which they were requested to classify one of two simultaneously presented stimuli, pseudowords containing the vowels /i/ or /o/ and pictures with positive or negative emotional facial expressions. Thus, stimulus pairings could be either congruent (/i/-words and positive expressions; /o/-words and negative expressions) or incongruent (/i/-words and negative expressions; /o/-words and positive expressions). We observed faster and more accurate responses for congruent over incongruent combinations (the simple effects were significant for positive but not for negative expressions). Thus, sound symbolic congruency (vs. incongruency) of an irrelevant stimulus facilitated responses, which accords with an automatic process contributing to valence sound symbolism and indicates that valence sound symbolism is deeply engrained in the human cognitive system. (PsycInfo Database Record (c) 2024 APA, all rights reserved).