This study investigated the effects of chemistry practical instructions for teaching and learning science process skill. Prediction and interpretation skills were the skills examined in this study. The study investigated how practical instructions in chemistry can assist students possess prediction and interpretation skills. To achieve these, survey research design was employed. Two research questions and two hypotheses guided the study. Purposive and simple random sampling techniques were used to select ten(10) secondary schools from the area of study and two hundred and five(205) students from the 10 schools. The population for the study was two thousand and sixty one (2061) senior secondary school chemistry students from the area of study. Two instruments were used for data collection; Practical Chemistry Achievement Test (PCAT) and Science Process Skills Assessment Format (SPSAF) which was a checklist with four(4) points rating used to assess ability of students during practical instructions in the laboratory. The practical instructions were on volumetric analysis carried out by students in the laboratory. SPSAT was validated by experts and trial tested on six (6) senior secondary two (SS11) chemistry students outside schools in the area of study.The results were validated using split-half reliability. This gave a value of 0.66which indicated that the instrument is reliable. PCAT was adopted from SS11 chemistry practical curriculum and thus considered as standardised. PCAT was used as achievement test. A lesson note guided the skills to be acquired. The values from SPSAT and achievement test scores from PCAT were analysed using mean and standard deviation for the research questions and t-test statistical analysis for the hypotheses, the findings revealed that chemistry practical instructions affect possession of prediction skills. The results also showed that chemistry practical instructions influenced possession of interpretation skills and achievement scores of students in chemistry practical. Recommendations were made among others that practical instructions should be emphasised for acquisition of prediction and interpretation skills and achievement in chemistry.