The objective of this research was to prove that the implementation of experiential learning could improve the speaking skill of the grade X students at SMA Katolik St. Andreas Palu. The research design was pre-experimental research. The population of this research was the tenth grade students at SMA Katolik St. Andreas Palu and the sample was class XC. The number of the sample was 28 students. The researcher employed cluster random sampling and adopted one group pre-test and post-test design. The pre-test was used to measure the students' skill in speaking before the treatment, and post-test was used to measure the students' skill after the treatment. Based on the result of both tests, the researcher found that the t-counted value is 13.01. The level of significance counted is set up at 0.05 and the degree of freedom (df) of the table value is 28 – 1 = 27. The researcher found that t-table was 2.052. It showed that t-counted was higher than the t-table. It means that the hypothesis of this research is accepted. In conclusion, the use of experiential learning was effective to improve the students' skill in speaking.