Exxon Corp. the world's largest oil company, yesterday said foreign currency exchange losses drove its second-quarter profits down by 3.4 per cent from those of a year ago.

Exxon, which operates in more than 100 countries, reported net quarterly earnings of $575 million ($1.28 a share) compared with a $595 million ($1.33) in the 1976 quarter.

Net losses from foreign currency transactions amounted to $44 million in the period against a $41 million gain a year earlier.

Excluding currency translations, Exxon said it would show a $65 million profit, instead of a $20 million loss on a quarter-to-quarter basis.

Worldwide revenues totaled $14.177 billion in the second quarter against $12.495 billion a year earlier.

For the first six months, Exxon said its net earnings were $1.22 billion ($2.72) on revenues of $28.5 billion, down 7.9 per cent from the 1976 first half net earnings of $1.325 billion ($2.96) on revenues of $25.6 billion.

R. J. Reynolds Industries Inc., of Winston-Salem, N.C., said its tobacco divisions was a major contributor to its higher second quarter results.

Earnings for the quarter rose 4.6 per cent from a year ago to $100 million ($2.05 a share) on sales of $1.66 billion against $95.6 million ($2.03) on sales of $1.36 billion. The company said sales of Vantage, its major low tar cigarette, increased 25 per cent over the same period a year earlier.

Inland Steel Co. reported a 21 per cent rise in profits for the second quarter to $40.3 million ($1.97 a share) on sales of $700.5 million compared to $33.25 million ($1.66) on sales of $621.07 million a year ago.

First half earnings dropped to $52.36 million ($2.54) on sales of $1.33 billion due to the severe winter weather, the company said. Last year's first half results were $59.22 million ($3.04) on sales of $1.19 billion.

Zenith Radio Corp. said pressure from less expensive imported electronics products resulted in its flat results for the second quarter.

Chairman John J. Nevin said profits were $7.5 million (40 cents a share) on sales of $245 million equal to te profits for the same period a year ago on sales of $227 million.

Pennzoil Co. reported second-quarter profits of $31.3 million (91 cents a share) on revenues of $286.1 million compared to $32.6 million (95 cents) on sales of $270.6 million for the same period a year ago.

Chairman J. Hugh Liedke said the company experienced substantial improvement in the second quarter and that higher results are expected in the remaining quarters of 1977.