This study describes a research focused on science teachers' evaluation of natural science literacy of research and comprehension competence in their students. Natural science literacy of research and comprehension competence is defined as an essential part of science literacy -- as a competence to find, evaluate and use science knowledge stored on the Internet (as a part of extended memory) to solve a problem in a science class and to construct students' own science knowledge. Online science literacy was defined in terms of the following aspects: basic skills (which include computer basics, web searching basics, and general navigation basics), locating information, finding a suitable website, locating the information on the website, critically evaluating the information according to its reliability and according to its relevance for the science class assessment. The data were collected through a 53-item Likert-scale questionnaire. The items were adopted from the TICA questionnaire for assessing students' general online reading competence. Science teachers from 5 different levels of pre-university education assessed their students' online science literacy in order to evaluate their students' competence to use the Internet as a storage and as a source of knowledge for teaching/learning process in the science class, to re-evaluate their online teaching practice and the need for implementation of natural science literacy of research and comprehension competence in their science curriculum. [This paper was presented at the 1st International Baltic Symposium on Science and Technology Education (BalticSTE2015) 'State-of-the-Art and Future Perspectives', June 15-18, 2015, Siauliai, Lithuania.]