The third largest U.S. oil company, Mobil Corp., yesterday said its fourth-quarter profits were 14 percent higher than results for the last quarter of 1976 while its full-year earnings increased by 6.3 percent.

Other domestic oil producers reporting increased earnings yesterday included Standard Oil of California, Shell Oil Co. and Standard Oil of Ohio.Decreased earnings were reported by Cities Service Co. and Murphy Oil Co.

Mobil said its fourth-quarter profits where $300.7 million ($2.84 a share against the year-ago period's $264 million ($9.08).

Mobil credited an improved performance by its domestic petroleum operations - including oil and gas production, manufacturing, transportation and marketing - which largely reflected higher prices and higher production of natural gas.

Mobil's natural gas production in the U.S. rose 3.1 percent to 2.4 billion cubic feet a day as a result of drilling in the Gulf of Mexico. But crude oil producution fell slightly, and higher costs of exploration trimmed its improved profits.

Refinery production was essentially unchanged from 1976, and petroleum product sales rose 1.4 percent.

Profits from foreign petroleum operations were up 17.5 percent to 402 million. Foreign results benefitted from North Sea crude oil production and from new production of gas in Indonesia.

Mobil estimated its 1977 revenues at $35.7 billion, but said the figure was not comparable with the 1976 figure of $27.6 billion because it excluded sales of Mobil's Montgomery Ward and Container Corp. subsidiaries.

Revenues from its Mobil Oil Corp. subsidiary totalled $29.2 billion in 1977, including excise and state gasoline taxes, a rise of $4.3 billion dollars from 1976. Montgomery Ward sales totalled $4.55 billion last year, a 13 percent increase over 1976. Container Corp's sales were $1.14 billion, a rise of $65 million from 1976.

Standard Oil Co. (California), the fourth-largest producer, said 1977 net income increased to $1.02 billion ($5.96 a share) from $880 million ($5.18) a year earlier. Revenues gained to $22.2 billion from $20.6 billion.

Fourth-quarter earnings were $273 million ($1.60), up from $268 million ($1.58) a year ago. Revenues totaled $5.7 billion, the same as in 1976.

The firm said 1977 gains stemmed from business abroad, as its domestic earnings fell $62 million due to higher federal and state taxes.

Shell Oil Co. reported record 1977 earnings but said the ratio of earnings to shareholder equity declined from 18 per cent to 16 percent.

Shell said its $735 million in earnings topped the $706 million a year earlier by 4 percent and was equivalent to $5.11 a share, up from $5.06. Revenues increased from $9.3 billion to $10.2 billion.

Fourth-quarter earnings of $192 million ($1.31 a share) were 36 percent more than the $141 million (99 cents) earned a year earlier. Revenues totaling $2.6 billion compared with $2.4 billion.

The company said it sold a record volume of gasoline last year, and that its oil products segment had an improved performance.

Shell said the rise for the quarter reflected higher revenues from natural gas and refined oils, mainly due to higher prices and increased sales volume of natural gas.

Cities Service Co. reported profit declines of 8.4 percent for the fourth quarter and 31 percent for the year.

Cities Service blamed the declines on lower margins for natural gas liquids, lower production of oil and gas, poor results from its minerals operations and a drop in profits from its chemical operations.

Fourth-quarter profits totalled $54.3 million $1.96 a share), off from the year-ago period's $59.3 million ($2.18). Revenues declined by 1.6 percent to $1.17 billion from $1.19 billion.

For the year, profits were $210.2 million ($7.62), off from 1976's $217 million ($7.98). Revenues were up 10.4 percent to $4.43 billion from $4.01 billion.

Standard Oil (Ohio) said it had 1977 net income of $181.1 million ($4.37 a share), up from $136.9 million ($3.55) a year before. Revenue rose to $3.52 billion from $2.92 billion.

Fourth-quarter profits rose to $70.2 million ($1.47) from $40.7 million ($1.06) a year ago. Revenues gained to $1 billion from $818.6 million.