A research study, mainly based on the notion of 'scientific literacy' from the Programme for International Student Assessment (PISA) 2003 assessment framework, was carried out obtaining data from the administration of an open written questionnaire with items covering three central scientific processes-describing, explaining and predicting scientific phenomena; understanding scientific investigation; and interpreting scientific evidence and conclusions-to 30 experienced in-service secondary school science teachers. The purpose was to analyse their views regarding the competences on the mentioned scientific processes assessed by Science PISA tests: which of the competences assessed were the most frequently identified by teachers, which of the competences they considered presenting difficulties for their students, and, finally, which activities they used in their classes to promote similar competences. Our results indicated that teachers had different perceptions of one or other scientific processes considered relevant for scientific literacy in the PISA framework. Their awareness of the expected students' difficulties did not necessarily match the competences intended to be assessed by either PISA or what they thought to be assessed. Moreover, their views differed depending not only on the type of scientific process but also on the underlying subject. Concern about the students' need of reading fluently with understanding and of paying special attention during the test time was also observed. © 2009 Taylor & Francis.