Joseph S. Murphy, the son of a labor organizer and a champion of the working class who rose to become Chancellor of the City University of New York, died in an automobile accident near Addis Ababa, Ethiopia, yesterday. He was 64.

It was not clear last night what Mr. Murphy, who had a long history of humanitarian and educational work in the East African country, was doing in Ethiopia.

Known for his genial manner and visceral sympathy for the plight of students, Mr. Murphy was able to rebuild and even extend academic programs during his tenure as CUNY Chancellor from 1982 to 1990, despite the system's financial woes.

Mr. Murphy, who learned to speak Yiddish from his mother, a Polish Jew, and Gaelic from his father, an Irish longshoreman, was a political scientist and author of two books.

He was known for his ability to combine a practical knowledge of politics with an enduring commitment to the poor and the working class. Highlights of his tenure as Chancellor included the introduction of child care services for working students and the expansion of adult literacy and collaborative programs with the public schools. He also started a summer remedial course that taught basic skills to incoming freshmen, and a $1.5 billion capital construction program to modernize 13 of the university's 20 campuses.

In an effort to make the administration more reflective of student enrollment, he sought out members of minority groups for top positions. In an editorial marking Mr. Murphy's retirement, The New York Times stated that his ''legacy of competence and commitment sets a worthy standard for his successor.''

Born in Newark, New Jersey, in 1933, Mr. Murphy attended the University of Colorado and received his bachelor's degree from Olivet College in Michigan in 1955. A recipient of a Woodrow Wilson Fellowship and others, Mr. Murphy received his doctorate from Brandeis University in 1961 and was an assistant professor at Brandeis until 1965.

Mr. Murphy served as director of the Peace Corps' Virgin Island Training Center in St. Croix from 1965 to 1966; as assistant Office Secretary in the Department of Health Education and Welfare in Washington from from 1966 to 1967; as an Associate Director of the Job Corps in the Office of Economic Opportunity in Washington from 1967 to 1968, and as director of Peace Corps operations in Ethiopia from 1968 to 1970.

He then returned to the United State and held a series of academic posts that eventually led him to head CUNY, the nation's third largest public university.

Mr. Murphy served as the Vice Chancellor for Higher Education for the state of New Jersey from 1970 to 1971. He was president of Queens College from 1971 to 1977 and president of Bennington University in Vermont from 1977 to 1982 until he was named Chancellor of CUNY.

Mr. Murphy had continued teaching at CUNY since his retirement as Chancellor and had served at a number of posts in Africa. He worked as an election observer in Ethiopia in 1992 and as a consultant for the Constitutional Commission in Addis Ababa in 1993. Mr. Murphy had also served as a member of the board of YIVO Institute for Jewish Research since 1993 and the UNESCO Global Project since 1992.

Mr. Murphy is survived by his wife Susan Crile, and his children from a previous marriage Lisa, Susanne, and Peter.