The article deals with examples of children’s creative word formation. Phonetic features of Spanish and Russian children’s speech are given special attention. An analysis of different phonetic processes in children’s speech and a comparison between them and the standard language are provided. Mistakes made by Spanish and Russian children are not only explained but also compared with each other in order to highlight their frequency. The most widespread phonetic features of children’s speech in Spanish and Russian are: onomatopoeia, epenthesis, substitution, contraction, metathesis, assimilation, and dissimilation. Every one of them is viewed and analyzed separately.