Profits of the Washington Post Co. climbed 88 per cent in the third quarter of 1977 compared with the same period last year, the communications company reported yesterday.

In an earnings statement that indicated particular strength in magazine and newspaper operations, the Post Co. said profits for the three months ended Oct. 2 totaled $6.6 million (79 cents a share) compared with $3.5 million (39 cents) in the same period last year.

The more rapid growth in per-share earnings reflects fewer shares of common stock outstanding. Over the past two and one-half years, the company was repurchased 1.76 million shares of class B common stock.

Higher earnings in the recent quarter contributed to profits of $22.5 million ($2.63 a share) for the first nine months of the fiscal year, a gain of 49 per cent over $15.1 million ($1.67) in the same months last year.

Revenues for the quarter rose 19 per cent to $102 million while nine-month revenues increased 17 per cent to $309 million. Newspaper division revenues rose 20 per cent in the third quarter with advertising linage in The Post newspaper up 9 per cent and in the Trenton (N.J.) Times up 4 per cent: magazine division revenues rose 21.5 per cent and broadcasting revenues rose 6 per cent.

Although the company does not provide data on profits for each division on a quarterly basis, yesterday's statement said pre-tax earnings from the newspaper and magazine (principally Newsweek) division "increased substantially" in the recent quarter.

Results for the first three quarters of 1976 were adversely affected by strikes in the early part of that year at a newsprint affiliate in Canada. In addition, there was afirst-quarter 1976 nonrecurring gain of $1.8 million (20 cents a share) from selling a radio station.

An insurance payment related to an earlier strike against The Post newspaper, of about $500,000 (6 cents a share) was included in second-quarter 1977 profits.

M. S. Ginn and Co., a Washington based office products distributor, reported profits of $241,569 (37 cents a share) in the first fiscal quarter ended Sept. 30, compared with $200,819 (31 Cents) a year earlier. Sales rose nearly 22 per cent to $9.2 million.

A cash dividend of 5 cents a share was declared payable Oct. 31 to stock holders of record Oct. 1.

Government Services Savings & Loan, of Bethesda, reported record second-quarter profits of $607,312 (75 cents a share) compared with $441,003 (54 cents) for the three months ended Sept. 30 last year.

For the first half of the year, Government Services earnings rose 31 per cent to $1.5 million ($1.41 a share) from $878,667 ($1.08). Chairman Arthur J. Phelan Jr. said the recent earnings gains were "somewhat above what seemed likely for the balance of the year.

Bankers Security Life Insurance Society profits for the nine months ended Sept. 30 were a record $2 million ($1.46 a share) compared with $1.75 million ($1.27) last year.

Chairman Leslie P. Schultz said new life insurance sales totaled $480 million vs. $366 million last year. Life insurance policies in force rose to $2.9 billion from $2.4 billion.