Hispanic students in Montgomery County, a minority population whose achievement test scores were described as "very disturbing" last year, scored higher on the same tests this year, although their scores were still far below county averages.

Blacks did just slightly better than last year on the tests and, overall, Montgomery students scored higher than they ever had before on the test that all Maryland students in grades 3, 5, and 8 must take. Montgomery also gave the tests to 11th graders.

Hispanics in Montgomery's third, fifth and 11th grades scored four to five points higher on the national California Achievement Test, a battery of tests given last fall in reading and math. The tests are designed to show how students in individual schools and school systems compare to national averages. Hispanic students in the eighth grade maintained the same scores. The four to five point increases were higher than gains registered by blacks, Asians or white students.

Those jumps, greeted with cautious enthusiasm by school district administrators, leave Hispanic students, on the average, with test results between 15 and 21 points lower than the district as a whole.

"I'm excited," Superintendent Wilmer S. Cody said. "The Hispanics are one of the minority groups that are the focus of an effort by the school system to improve their educational opportunities. I can't generalize on what the specific steps are that each school is making to address that need, but there is an effort."

Last year, Cody said the performance by Hispanic students was "very disturbing" because of inexplicable gains and losses in reading and math scores. Last year's results showed Hispanic students' average scores in grades 5, 8 and 11 had declined since 1980 by two to five points. The Board of Education has made minority achievement a priority, and Cody has pushed schools to narrow the gaps between the academic performances of the students.

"There's no way of knowing exactly what is causing it," said James Myerberg, testing coordinator for the school system. "It's probably some combination of what the kids bring to school and an increased effort to improve their scores."

Rolling Terrace Elementary principal Geraldine Meltz said her Takoma Park school has "done a lot of things" to help students.

"A big thrust has been to teach children not only how to take a test but to use their thinking skills," Meltz said. Extra tutoring is made available for the bilingual students, she said.

The high scorers among all the students taking the tests last fall were Montgomery fifth graders, who scored at the 87th percentile. That means that the average fifth grader in Montgomery earned higher scores than 87 percent of fifth graders across the nation, up from 84 percent last year and 79 in 1980. The 50th percentile is considered the national average.

In the five years that Montgomery has administered the California Achievement test, black students have made the greatest score gains, increasing between nine and 13 points in each category but still remaining the student population with the lowest achievement.

The only decline reported yesterday over last year's figures was among 11th grade Asian students, whose average score fell from 80 to 79 points. Overall, Asian students scored above the county average and above white students.

According to February 1984 figures, there are 13,371 black, 8,234 Asian and 4,937 Hispanic students in the 91,600-student system.