The Greyhound Corp. has reported second-quarter net income of $15.9 million (37 cents a share), a decrease from the $17.7 million (40 cents) earned during the same period last year.

Revenues for the quarter totaled $933 million compared with $950 million a year ago.

First-half net income was $24.9 million (57 cents) compared with $31.5 million (72 cents) last year. Revenues of $1.8 billion were unchanged from a year ago.

Board chairman Gerald H. Trautman said the decrease was a result of substantial losses suffered by the corporation's Armour Food Group. He said Armour results were hurt by inadequate profits margins caused by the inability to advance prices to cover escalating costs.

Reduced profits in Greyhound's intercity passenger operations hampered Transportation Group earnings, Trautman said. While a 5 per cent fare increases granted by the ICC in May and an increased number of passengers helped bus operations, rising costs more than offset those gains.

Armour-Dial's consumer products had a record profit for the second quarter, with good results in Dial and Tone soaps, Armour Star canned meats and Malina yarn product lines.

Food Service Group, which operates last food, cafeteria and restaurant facilities in industrial, military, commercial and other installations, as well as in Greyhound terminals, reported a 14 per cent increase in earnings in the quarter.

The Coca-Cola Co. yesterday reported record sales and profits for the second quarter and first half of 1977.

Cokes net income for the second quarter and first half of 1977.

Coke's net income for the second quarter was $95.9 million (79 cents a share) compared with $85.4 million (70 cents) for the same period last year.

Net income for the first half was $161.6 million ($1.32) compared with $144.4 million ($1.18) for the same period of 1976.

Second-quarter sales totaled $945.3 million, an 11.5 per cent increase over milllion. Sales for the first half reached $1.780 billion, a 14.8 per cent increase over the $1.508 billion for the corresponding period of 1976.

Board chairman J. Paul Austin said the dollar sales increases resulted from higher unit sales of soft drinks and sharply higher prices in the company's tea and coffee operations.