Purpose: Although the knowledge of decoding acquisition has expanded in the past years, theoretical information is still needed to guide practices concerning decoding skills in clinical and educational scenarios in languages other than English. Thus, we aimed to investigate the word-length effects on decoding acquisition regarding the time spent on decoding and the accuracy--the number of correct words/nonwords read per minute--in Brazilian Portuguese-Speakers. Methods: The study included 250 children enrolled in elementary school from first to fifth grade, and we used stratified random sampling to select the participants. To assess their decoding skills, we used a linguistically balanced list of words and nonwords designed according to Brazilian Portuguese decoding rules, word length variation, and the frequency of these words in the children's experiences. Results: Generally, data provide evidence of a stimuli length effect on accuracy and decoding time for words and nonwords. Data bring essential indicators for discussion in the acquisition and development of decoding since it adds another layer to investigate: intralinguistic features. Conclusion: The current findings contribute significantly to the area by indicating that the process of acquiring decoding has a multifactorial nature, and different interactions between variables can positively or negatively influence this process. Also, the present study may enlarge the knowledge by providing data from a transparent orthography encouraging more studies on the theme and cross-linguistic studies to understand how such variables here studied may vary in different orthographies.