In this study the researchers used the results of students' alternative to practical knowledge of Chemistry and their tests of theoretical knowledge of Chemistry to predict students' performance in Chemistry in MOCK-SSCE. This study adopted the expost facto design. All the SS two Chemistry students constitute the population for this study. Out of 33 schools only 15 schools met the requirement for selection as a science secondary school. Eight of these schools with a science student population of 128 (Male =64; female =64) were randomly selected and used for this study. The instruments used for this study were the students' alternative to test of practical knowledge of Chemistry (SATPKC) and the students' tests of theoretical knowledge of Chemistry (STTKC). These instruments were developed by the researchers and administered to the SS 2 science students. The reliabilities of the instruments were established during the pilot study using test -retest method. The reliability was calculated using Kuder Richardson (K-R21) and was found to be .94 for SATPKC and .89 for STTKC. The data for answering research questions were analyzed using the mean scores. Using multiple regression analysis for the hypotheses, the results show that male and as well female students' performance in a test of theoretical knowledge in Chemistry do not significantly predict their performance in MOCK-SSCE Chemistry theory examination. Male and female students' SATPKC score could not significantly predict their MOCK-SSCE mean practical scores. The overall relationship between SATPKC, MOCK-SSCE practical and MOCK-SSCE theory for male as well as female students were not significant. It was recommended that Principals of schools should ensure that both male and female science students are actively involved in practical work weekly as it will go a long way to enhance their performance during practical test and that efforts aimed at bridging the gaps between theory and practical performance of students in secondary school chemistry should not be gender discriminatory among others.