This article provides a fragment of a comparative-motivological study of motivational language awareness in the context of topical issues of child speech linguistics, and is based on the evidences of metalinguistic consciousness of preschool and primary school children of the mono- and bilingual society of Kazakhstan. The aim of the article is to identify common and specific features of perceiving motivated lexical units by bilingual and monolingual children in order to describe their motivational language awareness; the aim is reached by using current achievements of comparative motivology and data obtained during the experiment with the metalinguistic consciousness of preschool and primary school children (aged 5 to 10). The study employed both general scientific methods: description, comparison, statistical data processing, psycholinguistic experiment, interpretation, analysis, synthesis, classification and categorization, and linguistic methods: motivational-comparative analysis, componential analysis, including correlation technique, and segmental overlap of linguistic units. The research material consisted of motivated, semi-motivated and non-motivated one-word lexical units and set phrases of the Russian and Kazakh languages (180 language units), and 4320 units of children's meta-utterances. The authors regard children's motivational language awareness as a linguo-mental phenomenon consisting in the ability to realize rational interdependence of the sound form and meaning. Three stages of the experimental study in which 144 children took part were characterized. A new methodology was developed for the comparative analysis of the evidences of children's metalinguistic consciousness obtained during the experiment. A motivation scale was developed and became the basis for a new classification of words according to the degree of motivation. Common and specific features were identified in the perception of motivated vocabulary by monolingual and bilingual children. Due to the results of the study, the empirical and information base of the comparative-motivological theory was significantly expanded by including metatexts of children of different age groups (5-6, 7-8, 9-10 years of age) speaking one/two languages; the conceptual and terminological stock of the metalanguage of comparative motivology was enriched (motivating/non-motivating explanation, motivation index); current trends to describe motivational language awareness as a linguocognitive phenomenon were observed; new patterns of processing and perceiving word meanings by mono-bilingual children were identified; a new perspective of motivological study was outlined.