In this paper, we investigate who are the explainers who work is Brazilian science centres and museums. We used an online survey, which was answered by 370 people from 73 institutions out of a group of 200 scientific and cultural centres. Our results indicate that most of these professionals are young people between 18 and 25 years old, they hold a high school certificate or are attending university, and they have been working in this field for less than five years. Only a fifth declared that they had done professional training before starting their activities; about 60% said that they are not prepared to attend to disabled visitors. We believe that our study will improve the practice of science communication, contributing to the creation of training and professional courses.