Samsung Electronics Co, the world's top technology firm by revenue, will report record quarterly profit on Friday, powered by strong sales of its smartphones, but most interest will be in its 2012 spending plans and mobile sales numbers as it vies with Apple Inc for smartphone supremacy.

Samsung overtook Apple as the biggest smartphone maker in the third quarter, but is likely to have slipped back into second place in October-December as Apple sold a record 37.04 million iPhones. Samsung does not provide its own sales volume data and is likely only to give a growth rate from its third-quarter sales of 27.8 million smartphones. Analysts predict fourth-quarter shipments of 35-37 million.

The South Korean firm said earlier this month its October-December operating profit was likely to be a record 5.2 trillion won (2 billion pounds), up 73 percent from a year ago and up 22 percent from the previous quarter.

Investors will be looking for more detail on Samsung's investment plans for this year after parent Samsung Group announced a record $41.4 billion spending for 2012, with no detailed breakdown. Spending will be on everything from building factories to research and development activities to M&A and hiring.

Best known for making massive investments in new technologies ahead of rivals, Samsung is now banking on logic chips and OLED displays to repeat its roaring success in flash chips, computer memory chips and LCD flat-screens, even as a gloomy global economic and IT spending outlook forces peers to be conservative in spending.

What's important is the 2012 capex budget, as the headline sales and operating profit ... were already announced, Macquarie analyst Daniel Kim said.

The brokerage estimates Samsung Electronics will announce record investment of 29 trillion won ($25.76 billion), up by almost a third 32 percent from 2011.

Investment in system chips such as mobile processors and sensors used in smartphones, tablets and cameras is likely to exceed spending on its bread-and-butter memory chips for the first time, reaching 7.5 trillion won, or some 1 trillion won more than investment in memory chips, according to analysts.

Samsung trails Nokia in mobile phones, competes with Sony Corp and LG Electronics Inc in televisions, Toshiba and Hynix in chips and LG Display in displays.

RIVALRY WITH APPLE

Samsung only entered the smartphone market in earnest in 2010, some three years after Apple first introduced the iPhone with the touchscreen template.

Samsung may not have come up with the concept, but it has adopted Apple's breakthrough idea perhaps better than any other handset maker - and now seeks to offer the Apple experience at a better price, with better functionality.

Apple is Samsung's biggest client, buying mainly chips and displays, and the two firms are locked in a bruising patent battle in some 10 countries from the United States to Europe, Japan and Australia as they jostle for top spot in the booming smartphone and tablet market.

Apple, though, is streets ahead in profitability. Apple, which generates half its revenue from the iPhone, boasts a 37.4 percent operating margin versus Samsung's 11 percent, and its $17.3 billion operating profit is almost four times what Samsung earned from selling phones, chips, flat screens, TVs and fridges combined.

Shares in Samsung, also the world's top maker of memory chips and TVs, have climbed 20 percent in the past three months - and hit a life high of 1,113,000 won this week - outperforming a 3 percent gain in the KOSPI over the same period. On Nasdaq, Apple shares have risen 23 percent in that time, hitting a life high of more than $454 on Wednesday.

(Reporting by Miyoung Kim; Editing by Muralikumar Anantharaman and Ian Geoghegan)