Net Loss. Our net loss for the three months ended June 30, 2023 was $2,279,806, or 35% higher, as compared to a net loss of $1,689,994 for the three months ended June 30, 2022, for the reasons discussed above.
Comparison of the six months ended June 30, 2023 to the six months ended June 30, 2022
Revenue. Revenue for the six months ended June 30, 2023 and 2022 was $135,831 and $175,986, respectively. Revenue for the six months ended June 30, 2023 included development revenue of $98,443 and grant revenue of $37,388. Revenue for the six months ended June 30, 2022 consisted of grant revenue.
The grant revenue for the six months ended June 30, 2023 and 2022 related primarily to the $1.2 million subcontract with DTI discussed above. We completed our work under this subcontract in June 2023. For the six months ended June 30, 2022, grant revenue also included revenue related to a second subcontract with DTI. In September 2021, we entered into and began work under a $50,000 subcontract with DTI under a Phase I Small Business Innovation Research grant from the U.S. Department of Energy to develop a B-TRAN™-driven low loss alternating current SSCB. We completed our work under this subcontract in the first quarter of 2022.
Cost of Revenue. Cost of revenue for the six months ended June 30, 2023 and 2022 was $111,401 and $175,986, respectively. The cost of revenue relates to the development agreement and the NAVSEA subcontract with DTI for the six months ended June 30, 2023 and the subcontracts with DTI for the six months ended June 30, 2022. For the subcontracts with DTI, cost of grant revenue is equal to the associated grant revenue resulting in no gross profit.
Gross Profit. Gross profit for the six months ended June 30, 2023 and 2022 was $24,430 and $0, respectively. The gross profit in the six months ended June 30, 2023 related to the development agreement. We recorded no gross profit for the DTI subcontracts in the six months ended June 30, 2023 and 2022 and expect no gross profit from government grants that we are pursuing or may pursue in the remainder of 2023.
Research and Development Expenses. Research and development expenses increased by $1,089,786, or 70%, to $2,646,716 in the six months ended June 30, 2023 from $1,556,930 in the six months ended June 30, 2022. The increase was due to higher stock-based compensation expense of $566,394, personnel costs of $226,097, engineering services, primarily device packaging costs, of $187,433 and semiconductor fabrication costs of $121,376, slightly offset by lower other B-TRAN™ spending of $11,514. In the six months ended June 30, 2023, stock-based compensation expense included $415,553 related to performance stock units granted in December 2022 with a derived service period of 0.89 years.
General and Administrative Expenses. General and administrative expenses increased by $241,340, or 15%, to $1,828,926 in the six months ended June 30, 2023 from $1,587,586 in the six months ended June 30, 2022. The increase was due to higher stock-based compensation expense of $177,613, personnel costs of $106,291 and other net costs of $6,302, partly offset by lower Board fees and expenses of $48,866. In the six months ended June 30, 2023, stock-based compensation expense included $132,112 related to performance stock units granted in December 2022 with a derived service period of 0.89 years.
Sales and Marketing Expenses. Sales and marketing expenses increased by $123,645, or 27%, to $576,226 in the six months ended June 30, 2023 from $452,581 in the six months ended June 30, 2022. The increase was due to higher personnel costs of $72,172, search and placement fees of $33,750 and stock-based compensation of $26,961, slightly offset by lower other net spending of $9,238.
Loss from Operations. Our loss from operations for the six months ended June 30, 2023 was $5,027,438, or 40% higher, than the $3,597,097 loss from operations for the six months ended June 30, 2022 for the reasons discussed above.
Interest Income, Net. Net interest income was $219,647 for the six months ended June 30, 2023 compared to $2,462 for the six months ended June 30, 2022 due to the impact of higher interest rates on our money market account.