The objectives of this study were to; explore the possibilities and feasibilities of an online assessment of students' scientific inquiry skills; examine the psychometric properties of the test; ascertain the ability level of the 9th and 11th graders scientific inquiry skills. The sample consisted of the ninth and eleventh graders (N=118, 44 boys and 74 girls; age mean=16.42, and (SD) =1.25). In the test of scientific inquiry skills, students were required to use their cognitive skills to answer questions based on different subscales of scientific inquiry processes. The online assessment tool for scientific inquiry skills consisted of 99 items. The Cronbach alpha was 0.87 [alpha], and two subscales emerged with better reliability of 0.93 [alpha] and 0.90 [alpha] respectively. No significant differences were found between grades and genders concerning performances. The online assessment instrument for students' scientific inquiry skills proved to be feasible and reliable. The findings indicate that online assessment may provide teachers with an easy-to-use instrument for monitoring the development of students' scientific inquiry and reasoning skills. However, for this to be realized in Namibian, the government should try to improve the ICT [information communication and technology] infrastructures in most public schools as per their blueprint.