Stock Option Plans (Tables)

12 Months Ended

Dec. 31, 2012

Stock Option Plans [Abstract]

Allocation of stock based compensation expense

On January 1, 2006, BioTime adopted a new accounting pronouncement, which requires the measurement and recognition for all share-based payment awards made to BioTime's employees and directors, including employee stock options.  The following table summarizes stock-based compensation expense related to employee and director stock options awards for the years ended December 31, 2012, 2011, and 2010, which was allocated as follows:

	Year Ended December 31,
	2012		2011		2010
All stock-based compensation expense:
Research and Development	$	815,052	$	885,581	$	473,893
General and Administrative		1,028,910		916,832		619,838
All stock-based compensation expense included in expenses	$	1,843,962	$	1,802,413	$	1,093,731

Schedule of weighted average assumptions to calculate fair value of stock options

The weighted-average estimated fair value of stock options granted during the years ended December 31, 2012 and 2011 was $4.13and $4.89 per share, respectively, using the Black-Scholes Merton model with the following weighted-average assumptions:

	Year EndedDecember 31,
	2012			2011
Expected life (in years)		6.35			6.46
Risk-free interest rates		1.06	%		1.85	%
Volatility		98.88	%		106.49	%
Dividend yield		0.0	%		0.0	%

Summary of stock option activity

A summary of all option activity under the 1992 Plan, 2002 Plan, and the 2012 Plan for the years ended December 31, 2012, 2011, and 2010, is as follows:

	Options Available for Grant			Number of Options Outstanding			Weighted Average Exercise Price
January 1, 2010		2,087,168			3,477,000		$	1.13
Granted		(245,000	)		245,000			6.75
Exercised (1)		-			(401,410	)		1.56
December 31, 2010		1,842,168			3,320,590		$	1.13
Granted		(560,443	)		560,443			4.89
Exercised		-			(450,660	)		0.50
Forfeited/expired		21,468			(21,468	)		5.60
December 31, 2011		1,303,193			3,408,905		$	2.18
Granted under 2002 Plan		(280,000	)		280,000			4.75
Granted under 2012 Plan		(255,000	)		255,000			3.45
Exercised		-			(98,541	)		2.91
Forfeited/expired under 2002 Plan		-			(164,063	)		5.60
Added by 2012 Plan (2)		4,000,000			-			-
Reduce options ungranted under 2002 Plan(3)		(1,023,193	)		-			-
December 31, 2012		3,745,000			3,681,301		$	1.96

1)   This table excludes 250,000 options which were granted in 2008 outside the 1992 Plan and 2002 Plan, of which 125,000 were exercised in 2009 and the remaining 125,000 were exercised in 2010.

2)   During December 2012, the 2012 Equity Incentive Plan was approved by the BioTime Board of Directors making 4,000,000 common shares available for the grant of options.  This plan has not yet been approved by the shareholders.

3)   During September 2012, the 2002 Plan expired.

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Additional information regarding options outstanding

				Options Outstanding				Options Exercisable
Range of Exercise Prices		Number Outstanding		Weighted Avg. Remaining Contractual Life		Weighted Avg. Exercise Price		Number Exercisable		Weighted Avg. Exercise Price
				(years)
$	0.50		1,970,400		1.77	$	0.50		1,970,400	$	0.50
	2.30-8.58		1,710,901		4.06		4.43		1,004,007		4.36
$	0.50-$8.58		3,681,301		2.84	$	2.32		2,974,407	$	1.80

OncoCyte, OrthoCyte, ReCyte Therapeutics, Cell Cure Neurosciences, LifeMap and BioTime Asia [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Additional information regarding options outstanding

				Options Outstanding				Options Exercisable
Range of Exercise Prices		Number Outstanding		Weighted Avg. Remaining Contractual Life		Weighted Avg. Exercise Price		Number Exercisable		Weighted Avg. Exercise Price
				(years)
$	0.003-$0.10		5,216,226		6.95	$	0.37		2,790,371	$	0.34
	1.00-1.75		1,042,347		6.01		1.37		212,250		1.01
	2.05		1,550,000		7.43		2.05		681,250		2.05
	27.00-42.02		7,840		7.80		37.35		7,840		37.35
$	0.003-$42.02		7,816,413		6.92	$	0.87		3,691,711	$	0.77